It’s simply amazing that any components are able to withstand this nightmarish environment.

by Mike Mavrigian


A Dykes top ring from a Top Fuel engine.

(photo by author)


Note the missing plasma moly that was blown off of this top ring. This ring (and its companion set) saw a mere 24 seconds of running time, from startup to the end of the dragstrip. This particular engine powered the car to a 4.509-second run at 330 MPH.
It’s certainly no secret that Top Fuel drag engines produce horrific levels of power, to the tune of 7,000 to 8,000 HP and torque in the range of 6,000 lb-ft, currently shooting these cars to speeds in excess of 300 MPH. We thought that it would be interesting to dig into the particulars of the piston rings and bearings used in these over-the-top applications to gain an understanding of what these components are exposed to during a gut-wrenching 4.5-second blast down a quarter-mile stretch.

(photo by author)


These engines, limited to 500 CID, basically operate in the 8,400 to 8,500 RPM range during the entire run, utilizing a slipper clutch system that allows engine tuning within this very narrow RPM band. Engine configuration is loosely based on the Chrysler 426 Hemi format with a 90-degree cylinder angle, two valves per cylinder and hemispherical combustion chambers. Bore is at 4.19″ and stroke is at 4.500″ (combos may vary). Blocks are machined alloy forgings with ductile iron cylinder liners. These engines run “dry” with no liquid coolant. The absence of water passages result in increased block strength with the need to add a block “filler” for added rigidity. Cylinder heads are also CNC machined from alloy stock, fitted with two spark plug ports per cylinder, titanium intake valves and solid Nimonic 80A exhaust valves. Intake valves are approximately 2.45″ in diameter, with exhaust valves at around 1.925″. The valvetrain includes a billet steel camshaft, solid roller lifters and full-roller rockers, titanium valve springs and retainers. Crankshafts are billet steel, fitted with five bearing shells. Connecting rods are forged alloy. Pistons are forge alloy, with a three-ring package. Piston grooves are hard-anodized to prevent microwelding. Piston pins are secured with alloy pin buttons to aid in quick piston changeovers.
The supercharger is a 14-71 type roots unit, driven by a cogged belt. About 45.5 PSI boost occurs at wide-open-throttle. The engine oiling system is a wet sump setup with a capacity of about 16 quarts. Oil pressure is about 200 lbs. cold and about 160 lbs. during a run. The fuel mixture is primarily nitromethane, with about 15% methanol. Nitromethane features a high oxygen content, which means less air is required for combustion. Very rich mixtures are tuned. Coupled with nitromethane’s ability to absorb heat as it vaporizes, this helps to promote engine cooling. In other words, these engines run on tons of fuel and little air (instead of “conventional” 14.7:1 air/fuel, mixtures can be as great as 2:1). Fuel consumption is about 1 gallon per second. Whoof.


Here’s another view of a top ring’s plasma facing damage from the same engine.

Cylinder pressures are incredibly high, as much as 12,000 to 13,000 PSI (when detonation takes place, cylinder pressure is in the 16,000 PSI range). To put that into perspective, a Pro Stock engine may generate around 4,000 PSI of cylinder pressure. This is a major factor when considering the abuse experienced by the rings and bearings.

(photo by author)


To find out what’s happening in the Top Fuel ring arena, we spoke with Clevite’s Don Sitter and Federal-Mogul’s Scott Gabrielson, each of whom work hand-in-hand with teams in developing packages that perform.
According to Sitter, Clevite offers a hardened ductile iron top ring (their PC479 material, tradenamed Firepower). This ring is also available with a moly face, but Sitter noted that some builders prefer not to use the moly since firing pressures in detonation instances can sometimes cause the moly to chip off, potentially contaminating the oil filter.


The second ring from the same engine features an inner chamfer.
“There are two schools of thought with regard to top ring size,” noted Sitter. “We introduced a 0.078″ axial height ring with a 0.017″ Dykes step. Prior to that the most common top ring was a 1/16″ Dykes-style ring with a 0.017″ step. In working with various teams, we found that distortional effects caused the 1/16″ ring to reduce twist, essentially turning the ring into a beveled washer. It was obvious that substantial compression was getting past the top ring. To fight that, we went to the thicker ring, which worked out very well. A favorite saying of one of the Top Fuel builders we work with is ‘mass saves your ass,’ which was certainly true in this case. We also changed the second ring to a 0.078″ moly-faced version with a barrel (radius) face.
“Considering the other variables involved, however, you can’t look at the rings as a stand-alone of the overall equation,” Sitter said. “You must also consider cylinder finish, as some builders run a 280 finish followed by a plateau finish, while others go with an as-cut 280 or 400 wall finish. There are substantial differences in the tuning of these engines, including blower overspeed, static compression, amount of fuel delivery, timing, clutch management, etc. One team may have problems with pan pressure and sealing, and by switching to dual Dykes (the Dykes ring has a dam cut about a third of the way across the radial wall, which allows pressure to get behind the ring and push it against the cylinder wall), but the same deal might not work for another team.
“Top ring gap will range, depending on the builder’s experience, from as tight as 0.028″ to as much as 0.044″. The enormous heat generated during combustion necessitates these larger gaps.


Heads and piston/rod sets are removed after every run. Rings and rod bearings are always replaced after every run. To save time, some teams replace the entire piston/rod/ring/bearing set. After examination, pistons and rods may be reusable.
(photo courtesy Clevite)


Oil is also replaced after every engine shut-down, due to the excessive nitromethane fuel wash.
(photo courtesy Clevite)

“Some crew chiefs have told me that when we went to the thicker rings, pistons ran cooler due to the decreased thermal resistance in a dry block,” Sitter said
Sitter noted that taper-faced second rings, regardless of material, tend not to be effective because any compression that leaks past the top ring will load the face of the taper ring, causing the ring to be pushed away from the cylinder wall, increasing blowby and pan pressure. A barrel-faced ring fights this because the tangent point is closer to the top of the ring. Sitter also noted that Clevite is introducing a new second ring in 2007, a reduced radial wall 0.078″ barrel-faced ring positive twist ring. This prevents the second groove from undercutting the top groove, allowing the No. 2 land to better withstand the primary firing pressure at the top ring. The reduced radial wall will also help to bring the mass back to close that of the original 1/16″ barrel ring.
“The laws of physics are routinely being broken in Top Fuel,” jokingly noted Federal-Mogul’s Gabrielson. “What these teams are accomplishing is nothing short of incredible.”
“Dykes rings seem to work very well in supercharged applications,” Gabrielson said. In the beginning, top ring materials were generally chrome plated stainless steel, but about 15 years ago this progressed to the use of ductile iron with a plasma moly face. Stainless tends not to be very compatible, with the chrome plate tearing up cylinder walls quicker. Granted, the cylinder liners are replaceable, but since the teams have only about 75 minutes to service the engine between rounds, if a wall goes away, the team will usually just swap out the entire block to save time.
“The most common top and second ring sizes have been 1/16″. Our experience has been that some crew chiefs have used Dykes second rings in place of rectangular rings, but with mixed results,” Gabrielson said. Some experimentation with wider Dykes rings (5/64″ face) has taken place, with results showing superior resistance to twisting. We’ve seen mixed reviews with regard to the wider rings, with some teams claiming improvements and others saying that they saw no change. Top rings simply don’t last, and are usually destroyed during the run, so ductile iron plasma-faced second rings are the norm, since you need a durable backup ring. Ring fracture isn’t a big issue, since the incredible cylinder pressure seats the ring on the bottom of the groove, eliminating flutter. The top ring simply fails due to pressure and heat, leaving the second ring to serve as the essential backup compression ring.”
Oil rings, because of the pressure formed around the expander, can actually be smashed. Regardless of the brand, style or type of material, rings don’t make it through more than one run, so they’re replaced as a matter of course between rounds.

tf10Detonation events will damage main bearings as well. These mains were exposed to a single run. Note the severe scoring, the result of enormous forces created by the astronomical cylinder pressures.
(photo courtesy Clevite)

tf091Here are three upper rod bearings that experienced a single run. Note the extrusion of material, which is especially evident in the center shell seen here.
(photo courtesy Clevite)

tf08Wet sump oil systems are a must due to the need to change contaminated oil quickly.
(photo courtesy Clevite)


“While rod bearings haven’t changed much in the last eight years,” noted Clevite’s Sitter, “there was a series of changes in 2004 involving NHRA-mandated reduction of nitro, blower overspeed, etc., in an effort to regulate speed (since speeds were approaching 330 MPH). It’s taken two seasons to get back to performance levels of 90% nitro. Now, we see more detonation and more damage to upper rod bearings. Again, because of the incredible cylinder pressures, upper rod bearings actually begin to extrude (about 0.080″ at the ends), making them appear as flanged bearings. If materials change, moving to a mild grade steel, for instance, this would still present a liability to the crankshaft, since the harder extrusion would get into the journal fillet, possibly creating a stress area. At the present time, Top Fuel crankshafts are generally changed out anywhere from three to five runs (some teams stretch this to as many as 12 runs). Since these crankshafts cost around $3,500 each, and since the team may make about 200 passes each year, the difference between buying 20 cranks versus 60 cranks per year would present a real financial problem.
“A number of detonation management issues need to be addressed before we blindly change rod bearing design,” Sitter said. “The problem isn’t the bearing … rather, it’s how the bearing is being treated. One analogy is that rod bearings can be viewed as the circuit breakers in the system.”
“Rod bearing clearances have decreased,” Sitter said. “Years ago, it was not uncommon to see rod bearing clearances in the 0.005-0.006″ range, with main bearings in the double digits. Today, rod bearing clearances range from 0.0035-0.0045″, and main bearing clearances are in the area of 0.0045-0.006″.”
“Typically, Top Fuel bearings are not coated with a special anti-friction treatment.,” Sitter said. We’ve tried Tri-armor, but there does not seem to be any big advantage. They work as expected, but don’t offer the kind of benefits you need in a Top Fuel application. The issue focuses more on how to prevent the engine from shedding parts when detonation occurs. Our V bearing works great.

This is constructed of lead indium plated overlay on a cast tri-metal lining with a conventional steel backing. This does a good job of managing the detonation environment. While the moly coatings, such as our Tri-armor treatment, survive very well, this offers no particular margin with regard to detonation events.
“Top Fuel applications experienced thrust bearing problems a few years ago, which prompted us to make several improvements to the flanges, including the use of lead indium on the thrust faces, and to work with teams and crank manufacturers with regard to thrust face surface finish,” Sitter said. “We did note that those teams having thrust bearing problems were all using a particular oil, which convinced me that some oil brands do perform better than others.”
By the way, most teams run 70-90 W synthetic oil. It’s interesting to note that because of the excessive nitro fuel wash that runs through the engine, fuel dilution of the oil is so great that the engine oil must be changed every time the engine is shut off (even following a warm-up). As noted earlier, since these are dry engines with no liquid cooling system, this excessive fuel wash helps to manage temperatures, basically preventing the pistons, heads and valves from melting.
The incredible cylinder pressures are so great that it’s not at all uncommon for hefty wrist pins to bend. In addition, rod small ends are elongated and rod big end saddles can be pulled out. When you consider their environment, it seems a miracle that any rings or bearings can function and allow these engines to perform their jobs, yet they do, weekend after weekend, all year long.
By the way: ever notice that the exhaust tubes are always turned up, with exhaust pulses exiting upwards? This isn’t just for appearance. This is due to the enormous cylinder pressures. By directing the exhaust upwards, this helps to generate greater chassis downforce for better tire bite and stability. If the tubes aimed downward, the business-end of the car might very well be lifted off of the track surface.

Typical burnout to transform the tire surface to a low-durometer, sticky state for increased traction.
(photo courtesy Clevite)


These engines are typically not fully assembled or dyno’d in the shop. Rather, they’re assembled in the car. Each run include fresh rings, rod bearings, and oil.
(photo courtesy Clevite)


Gone in about 4.5 seconds, currently reaching a trap speed of around 330 MPH.
(photo courtesy Clevite)




Efficient lubrication plus reduction of parasitic power loss.

By Mike Mavrigian

photos by author



A street engine, and many race engines, utilize a “wet sump” system to deliver pressurized oil to the engine’s internal rotating and reciprocating assemblies. Engine oil is stored in the oil pan sump (the big reservoir section of the pan). The oil is picked up by a mechanically driven oil pump, which obtains the sump’s oil via a submerged oil pickup. As the pump rotates (the pump runs whenever the engine runs, since it’s driven by the crank or indirectly via the distributor drive), oil is pressurized and distributed from this main source throughout the engine as oil is distributed through the oil passages in the block, crank journals, main bearings, rod bearings, and, eventually, to the valvetrain. Although this system does deliver oil to all required areas, the oil must be pushed through all of these passages to eventually route to the upper end of the engine. The delivered oil is then free to drain back to the sump, with delivery and drain-back serving as an ongoing cycle during engine operation.
A “dry sump” system takes a different, and much more direct approach. This uses an externally-mounted oil pump, which takes advantage of external plumbing to directly deliver oil to the engine. The oil pan does not feature a sump reservoir. Instead, the dry sump pan serves only as a containment cover and as a location from which oil can be returned to the reservoir. The oil reservoir (oil supply) is a remote container (usually mounted in the cockpit or other convenient location in the race vehicle). In very basic terms, the external pump pulls oil from the remote reservoir, and then pushes the oil (under pressure) to wherever the plumbing directs it. In this manner, oil can be directly sent to the main bearings through a block port, oil can be delivered directly to the valvetrain with one or two plumbed hoses (depending on the application) and oil can be directly delivered to a turbocharger, etc.
Dry sump pumps are offered in stages depending on how many direct-delivery and return (scavenge) routes are required. The advantages include immediate oil delivery to specific areas and elimination of oil starvation caused by angle and centrifugal forces (when the race car accelerates, brakes or turns), which may momentarily expose an in-the-pan oil pump pickup, allowing air (not oil) to travel throughout the block. In other words, the potential for oil aeration is eliminated. Since the scavenge section(s) of the dry sump pump pull oil from the dry sump pan, this creates a vacuum, pulling excess oil from the surfaces of the crank and rods, reducing parasitic drag (which means more efficient use of engine power).
When plumbing a dry sump system, size requirements may vary somewhat, but a general rule of thumb is to use -10, -12 and -16 hose, fittings and hose end sizes (for some turbo applications, a -6 hose size is recommended). Generally, a larger size is required for the return hose that runs out from the pump to the remote oil reservoir (for instance, if -12 hoses are used for all feeds, a -16 hose would be used for oil return to the reservoir).
Although a dry sump oil pan will feature threaded bungs to accept suction line fittings (where drainback oil is pulled by the pump), plumbing to the block or other areas may require drilling and tapping or the purchase of special adapters. Typically, if an adapter is needed to feed oil to the block’s main galley (at the stock oil filter location, for example), aftermarket adapters are readily available for all popular blocks. By the way, if you’re using the OE filter location for oil feed, you’ll need to remotely locate an oil filter.
An externally mounted dry sump oil pump is most commonly driven by a notched belt (toothed belt often referred to as a Gilmer belt), directly from the crankshaft snout (a pulley is installed on the crank, with the belt connecting the crank pulley to the pump pulley). Dry sump pumps, via the proper pulley diameters, are generally driven at about half of crankshaft speed.
Dry sump pumps driven by the nose of the camshaft are also available, with the pump mounted on the face of a special timing cover.


  • Superior consistency of oil pressure
  • Oil isn’t pushed away from the oil pickup during severe turns, acceleration or braking, as may occur with a wet sump system
  • Adjustable oil pressure
  • Increased oil system capacity
  • Shorter profile pan, allowing engine to be mounted lower in chassis for lower center of gravity.
  • Increase in engine power
  • Positive oil delivery to critical areas of the engine
  • Cooler oil supply (since the oil is quickly returned to the remote reservoir instead of being stored in the hot oil pan)

A dry sump pump features a pressure section and a scavenge section. The pressure section delivers oil to the engine, while the scavenge section pulls “leftover” oil from the dry sump pan and sends it back to the remote oil reservoir.
Dry sump pumps are built in “stages, with one pressure section and one or more scavenge sections. The additional scavenge sections (as few as one, as many as 6) allow oil to be scavenged more quickly and efficiently from specific areas of the engine, instead of waiting for the oil to be drawn down into the pan for scavenge pickup.
A typical 2-stage dry sump pump features 1 pressure section and 1 scavenge section.
A typical 3-stage dry sump pump features 1 pressure section and 2 scavenge sections.
A typical 4-stage dry sump pump features 1 pressure section and 3 scavenge sections.
A typical 5-stage dry sump pump features 2 pressure sections and 3 scavenge sections.
A typical 6-stage dry sump pump features 2 pressure sections and 4 scavenge sections.

A typical dry sump oil system features a host of components including:

  • Dry sump pump
  • Dry sump pump pulley
  • Toothed pump drive belt
  • Pump fittings (male -AN 37-degree flare to accept -AN hose ends)
  • Pump mounting bracket
  • In-line screened oil filter(s)
  • Remote in-line oil filter and filter mount
  • Remote-mounted oil tank
  • Breather (separate or on-tank)
  • Oil filter block-off plate for engine block
  • Required -AN hose assemblies


The dry sump system oil tank simply serves as the primary oil reservoir. The tank receives the oil scavenged from the outlet ports of the dry sump pump. Once the oil enters the tank’s inlet fitting, the oil hits an internal “splitter” that directs the oil in a specific stream. After hitting the rolled inner tank wall (this softens the impact of the oil) it rolls onto an upper baffle, allowing the oil to flow out in a thin sheet, which promotes the release of air that might be trapped in the oil. The oil then falls into the reservoir, waiting to be pulled out and recycled through the engine.
A large portion of the tank volume is air, which exceeds the volume of oil being pulled from the pump. To allow air to escape, the tank must be vented, which also benefits the system by lowering atmospheric pressure in the crankcase.
Dry sump tanks are available in capacities ranging from 1 gallon to 5.5 gallons.

Here’s a 2-stage dry sump pump fitted to a Honda race engine (the engine block was rotated on the stand to better show the pump and pan). A pair of -12 AN hoses connect the dry sump pan to the pump.


This overhead view shows the pump side-mounted to the block. The toothed Gilmer belt connects the small diameter toothed crank pulley to the pump pulley. The dry sump pump runs at approximately half of the crank speed. Notice the two hose ends on the top of the pump. The larger -16 will be plumbed to the upper port of the reservoir, serving to return oil from the pump’s scavenge back to the tank. The -12 will be plumbed to the block’s main oil port to feed the engine.

The -16 hose shown here plumbs scavenged oil from the pump to the remote reservoir. A fitting/hose connection at the bottom of the reservoir is the feed line from the reservoir to the pump. Note the oil delivery -12 hose to the oil filter adapter on the block. The reservoir shown here was mounted on our shop’s engine stand for display purposes. The reservoir will be mounted in the race car cockpit area (obviously with longer hoses).

A dry sump “kit” including reservoir, pan, pump, belt, crank pulley and pump mounting bracket. The angled fitting at the top of the reservoir will accept a breather.

This Aviaid dry sump pump mounting bracket features multiple threaded holes, providing plenty of latitude when mounting the pump for optimum location (for pulley alignment).

Here, our pump is mounted to the bracket using four 5/16″ bolts.

The toothed pump drive belt slips onto the pump pulley by engaging the teeth. The pulley is also adjustable fore/aft to fine-tune belt alignment.

Here, you can see the feed hose at the bottom of the reservoir tank, where the pump draws oil from the tank to the pump.

A 5-stage dry sump pump. Note the four scavenge hose connections at the pan.

An in-line oil filter plumbed from the dry sump pump to the filter, then into the block.

This race engine features scavenge/vent plumbing from the valve cover to aid in reducing parasitic drag and to vent the engine within a contained system.


Quick-connect couplers allow quick connection/disconnection of oil hose assemblies without loss of oil. The Jiffy-Tite coupler shown here features valving that shuts off when the connection is uncoupled. Use of these quick-connect couplers allow for faster engine removal with no oily mess.

When routing your plumbing hoses, make sure they don’t interfere or rub on any moving parts. Here the two hose ends are installed at a sufficient angle to prevent the hoses from touching the timing belt, and the hoses are secured together with an aluminum hose separator.

This oil reservoir features a breather fitting at the top, two scavenge fittings near the top, and one feed-out fitting at the bottom. (Photo courtesy of Peterson Fluid Systems.)

Instead of attaching a breather directly to the top of the reservoir, a remote breather can like the one shown here can be mounted remotely. (Photo courtesy of Peterson)


A dry sump system allows multiple oil feeds. Here a direct oil feed hose is plumbed to a turbocharger using a -6 AN hose.


Dry sump pumps are built in stages. The ports marked “IN” are for scavenge hoses and oil feed from the reservoir. The ports marked “OUT” are for pressure output from the pump and for return to the reservoir. Pulleys are keyed and provide a positive retention onto the pump drive shaft. (Photo courtesy of Barnes.)

In this plumbing hookup, we installed -12 male AN flare adapters to the pan to accept -12 hose ends. For the scavenge hose being installed in this photo, we chose a straight hose end for the pan connection and a 45-degree hose end at the pump. The capped fitting seen on the scavenge side of this pump will be used to connect to the reservoir’s bottom port to pull oil from the tank to the pump. Due to the range of hose end shapes available, it’s easy to create direct and tidy plumbing regardless of the engine configuration.

Always use aluminum -AN wrenches to service the hose end connections.


Soft aluminum wrenches prevent gouging the hose end couplers, and prevent damaging the hex corners.

CAUTION: If an engine fails (by that we refer to any problem that allows metal debris to enter the oiling system), don’t neglect the dry sump system during the rebuild process. The external oil pump must be disassembled, cleaned and inspected for damage (in-line filters can be plumbed in-line in the oil return lines during system installation, which is always a good idea, But even if a filter is present, the pump should still be inspected). Naturally, the remote oil reservoir should also be cleaned. However, many people tend to overlook the hoses (and a remote oil cooler, if present).
If you suspect metal contamination, although you may try to flush and clean all of the hoses, if you’re dealing with hoses that you can’t also visually inspect (long hose or hose fitted with angled hose ends), the safest route may be to replace the hoses. That’s a call you’ll need to make on your own, but be aware that random debris might be lodged in the hose inner wall. If you’re certain that the hose is clean, by all means feel free to re-use it. If you have any doubts, though, spend the money to replace it.
As far as external oil coolers are concerned (and this holds true for any remote cooler, whether it’s for the engine, transmission or axle drive), if you suspect that metal debris has entered the cooler, replace the cooler. Unless you have access to an X-ray machine, you’ll never be certain that the cooler tubes are clean. If you reuse a contaminated cooler, you’re asking for trouble because the debris can dislodge and run into the engine. Considering the cost of a cooler (even the most expensive type) versus the cost of the engine, it’s good insurance to toss the suspect cooler and buy another.


Machined billet aluminum oil filter block on a Honda. This engine was fitted with a dry sump oil system. Note the finger pointing to a round plug. This was the OE location for a crankcase breather. Since the dry sump system pulls vacuum in the oil system, the block breather wasn’t needed, so we made a press-in aluminum plug on the lathe.

All photos by author unless otherwise noted.


2-stage dry sump system


2-stage cam-drive dry sump system.


3-stage dry sump system.


3-stage cam-drive dry sump system.


4-stage belt-drive dry sump system.


4-stage cam-drive dry sump system.


5-stage dry sump system.

(All example plumbing illustrations courtesy Aviaid)Sources



(dry sump pans)
For more information, dial 1-800-652-0406, ext. 13401
Online, visit

(dry sump pumps)
For more information, dial 1-800-652-0406, ext. 13402
Online, visit

(dry sump oil systems)
For more information, dial 1-800-652-0406, ext. 13403
Online, visit

For more information, dial 1-800-652-0406, ext. 13404
Online, visit

(wet and dry sump pans)
For more information, dial 1-800-652-0406, ext. 13405
Online, visit

(pans, accusumps, filters)
For more information, dial 1-800-652-0406, ext. 13406
Online, visit

For more information, dial 1-800-652-0406, ext. 13407
Online, visit

(aluminum dry sump pans)
For more information, dial 1-800-652-0406, ext. 13408
Online, visit

(dry sump oil pumps)
For more information, dial 1-800-652-0406, ext. 13409
Online, visit
(pumps, pans)
For more information, dial 1-800-652-0406, ext. 13410
Online, visit

(pumps, steel and aluminum pans)
For more information, dial 1-800-652-0406, ext. 13411
Online, visit
(dry sump oil tanks)
For more information, dial 1-800-652-0406, ext. 13412
Online, visit

(dry sump pump systems)
For more information, dial 1-800-652-0406, ext. 13413
Online, visit

(B&B pans)
For more information, dial 1-800-652-0406, ext. 13414
Online, visit

Porsche Speed Record Run At Talladega

Porsche Speed Record Run At Talladega

We work and play with the big boys.

by Mike Mavrigian

photos by author

pcna10Our three cars in the Talladega garage during testing week.

As Forrest Gump often noted, you never know what you’re gonna get. In August and September of 2005, Precision Engine editor Mike Mavrigian was contracted by Porsche Cars North America for technical involvement in a “speed record run” involving their high-dollar Carrera GT cars at the Talladega Superspeedway. The official event took place September 1, 2005 at the Talladega, Alabama track, located about 50 miles east of Birmingham.
The Carrera GT is a $440,000 exotic street car featuring an all-carbon-fiber monocoque and body, equipped with an alloy-block 605 HP 5.7L V-10 engine. The motor features titanium connecting rods, a “lightweight alloy” crankshaft, titanium valves and springs, etc. The engine’s light rotating and reciprocating mass allows it to quickly zip to 8,000 RPM in the blink of an eye (sounds like a Formula One motor). The stock Carrera GT used for the record at Talladega was produced at the Porsche factory in Leipzig, Germany and was upgraded with safety equipment only, including a six-point harness and Michelin Pilot race tires designed to handle the forces generated by the car when at speed on the severe 33-degree Talladega banking.
The goal of the event was to set a number of specific speed records with the GT, which serves as a repeat of history for Porsche fans (30 years ago, Mark Donohue set a track record at Talladega with a 1,000-HP Porsche 917/30 race car at 221 MPH). In this 2005 event, David Donohue (Mark’s son) was enlisted as the pro driver, with celebrity Jay Leno as the second driver. David clicked off a 196.301 MPH lap (a record for the production street car), while Jay handled the standing 1-mile and 5-mile runs.
Donohue also set records for the measured mile at 198.971 MPH; and the measured kilometer at 195.755 MPH. Leno set three standing-start speed records in the same car, the fastest being 156.603 MPH. Flying records are recorded from a rolling start, while standing speed records are recorded from a complete stop.
All of the record runs established during the September 1, 2005 event were recorded and verified by the Grand American Rolex Sports Car Series sanctioning body.
“It amazes me that we were able to go nearly as fast in a 2005 street car as David’s father did in a 1,000 HP race car,” said Leno, who is an avid automotive historian and collector. “This Carrera GT has air conditioning, a stereo, a navigation system and a cockpit full of leather and still goes almost 200 MPH around this course. It’s outrageous.”
Leno, by the way, did an outstanding job as a driver. We were impressed with his focus and his consistency. He started off in practice running 1.16 minute laps, dropping his lap times with each successive lap, down to a 54-second lap time (only 3 seconds off of the pro driver’s times). Jay also provided, as you’d expect, comedic relief during the event. He’s a down-to-earth car guy and a true gentleman.
Our involvement was relatively minor, helping to prepare the cars (setup, seat harnesses, radio systems, etc.) and to procure, deliver and set up all of the garage and pit equipment (platen chassis setup stand, race jacks, hand and pneumatic tools, compressed nitrogen, pit awnings, radio systems, refueling equipment, pyrometers, etc., etc.). The Porsche training instructors at Porsche’s Atlanta training center performed the tedious job of chassis adjustment, which was critical.
As part of his preparation duties, Mavrigian enlisted a handful of product sponsors to participate in this historic program. Chrysler loaned a new Dodge Ram quad cab truck equipped with the turbo diesel engine as the equipment-trailer tow vehicle. Trailex loaned us a new all-aluminum enclosed trailer (normally intended to haul precious race or collector cars, although we loaded it with tools and equipment). Sunoco graciously supplied the 100-octane GT fuel (a whopping 100 gallons), delivered direct to the track. Goodson Shop Supplies provided a range of materials including shop aprons, spill absorbent, shop towels, etc. Polaris loaned a kick-ass ATV, their Ranger model (in Porsche Guards Red color, no less. we fell in love with this thing…no matter how hard we tried, we could not get this thing stuck in the boonies behind our tech shop). Ringers also supplied a healthy package of their work gloves and radio belts. Our thanks to all of these participants.


We prepped three Porsche Carrera GTs prior to the week-long testing session at Talladega. Prep took place at Porsche’s training center in Atlanta.


The engine is a V-10 5.7L high-buzzer that yanks 605 HP at around 8200 RPM.


Underneath all of the carbon-fiber covers lurks the all-motor V-10. The Y-shaped section of carbon fiber you see here is actually part of the car’s frame. Note the horizontally-mounted coilovers.


This training cutaway section of the right front reveals the high-mounted rack, the huge 15″ ceramic brake rotor and adjustable horizontal coilover. All of the radius rods are titanium.


We spent three solid days at the Porsche Service Training Center during car prep.


A rear view of the Carrera GT. The speed-activated rear wing rises up via solenoids and can be locked in the raised position.


This cockpit view shows the 2-way radio installation that we performed on all of the cars while at the training center. Since we were forbidden to drill any holes, we improvised by taking advantage of existing under-console-holes (and used plenty of nylon wire ties).


We set up a Longacre platen in the Talladega garage, which allowed us to check and adjust suspension corner loading and wheel alignment at the track.


Would you buy a car from these jokers? Jay Leno hams it up with Precision Engine editor Mike Mavrigian during a break in the pits.


We had the Talladega track all to ourselves, which is sort of eerie considering the vast size of this track. This shot was taken during initial setup of our pit area.


Chrysler was kind enough to loan us a Dodge Ram crew cab equipped with the turbo diesel as our tow vehicle. We cruised in comfort with torque to spare (the truck didn’t even know the trailer was back there).


Trailex provided one of their gorgeous all-aluminum enclosed trailers, which we used to haul all of our tools, ATVs, supplies and pit equipment.


The official crew pass for Porsche’s Carrera GT Speed Record Run.


Jay Leno (in helmet) and pro driver David Donohue. Leno did an impressive job on the track, and kept us in stitches during the breaks.


At speed on the front straight at Talladega.

Leno and Donohue in Victory Lane following the record runs. Porsche has decided to auction the silver car and to donate all proceeds to the Katrina Hurricane Fund.

Editor’s Note: While this program and this article doesn’t deal with the builds of the Porsche engines directly, we thought our readers would nonetheless enjoy a peek at what took place. After all, it’s not every day that you get a chance to melt under the Alabama sun at a legendary track, prep ultra-exotic performance toys or hang with the likes of Mr. Leno.

Street Performance & Racing Piston Tech


Insight into the world of go-fast slugs.

by Mike Mavrigian

photos by author


It should come as no surprise that piston technology has evolved over recent years, largely due to superior material availability and the advent of precision CNC-machining capabilities. While a custom piston order may have once required four to six weeks or longer, computer modeling and CNC processes have cut the waiting time in some cases to a mere few days (naturally, depending on the piston maker’s schedule. Bear in mind that top piston makers are besieged by orders from pro race engine builders prior to the start of each season, so factor this into your expectations). For popular movers such as smallblock Chevy applications, many designs once viewed as “custom” in nature may now be available as in-stock items, ready to ship.
Here, we’ll focus on forged racing pistons. While hypereutectic pistons (high-silicon content castings that are much more dimensionally stable under thermal stresses than a common type aluminum casting) are perfectly adequate for high performance street motors, as well as many race applications, they’re nonetheless castings, which are less ductile than forgings. In other words, if it’s gonna break, a casting will tend to shatter as opposed to a forging, which will go “plastic” before it breaks through.
The two most common alloy materials used in today’s forged pistons are 2618 and 4032 aluminum. The 2618 material is a nearly pure aluminum with very little silicon content.
According to Probe’s Chris Huff, this material provides increased fatigue resistance, with a tendency to bend rather than crack.

4032 alloy, on the other hand, possesses a high silicon content (usually about 12-14%), making it harder, which means that it won’t plasticize as readily as 2618. As a result, pistons made from 4032 need to be thicker and heavier to provide the needed strength. However, the higher silicon content provides a harder wear surface, and subsequently longer piston life. According to Chris, 4032 is a good choice for naturally aspirated street applications (and for relatively lower turbo boost pressures), while 2618 is a better choice for higher boost pressures (16 lbs or more). Top Fuel applications, where extremely high cylinder pressures are a constant, 2618 is the common material of choice. While 2618 alloy provides outstanding high-temperature characteristics, greater wall clearance is usually required due to this material’s tendency to expand and contract.
Dave Calvert at CP Pistons notes that although 4032 aluminum can be an acceptable choice for street and some supercharged applications, the majority of their pistons are manufactured from 2618 forgings, since this grade of very pure and strong aluminum allows precise thermal growth calculations, allowing engineers to accurately predict piston dimensional changes during anticipated cycling operation in any given engine and its track application.
The many technology changes in pistons over the previous five years or so involve increasing piston strength and resistance to fatigue. An example, according to CP’s Dave Calvert, is use of the “box style” (also called strutted) pin boss design to increase rigidity. These reinforcing struts stabilize the pin bosses and the ring grooves, adding dramatically superior strength around the piston periphery.


CNC machining offers precise and repeatable dome configurations.


Top ring grooves are typically hard-anodized to prevent microwelding.

We spoke with Barry Rabotnick, the chief tech honcho at Federal Mogul regarding that firm’s current developments. Barry noted that they’ve recently introduced a new line of high-performance/race entry-level forged pistons that offer big-time benefits at a street-level price. The new line features lighter weight and shorter skirts, with a webbed reinforcement underside. The pin boss area has been shortened up, and cut-throughs are machined into the webbing for quick oil drainback. A notable feature involves a “figure eight” skirt configuration that is slightly larger on the thrust side (a very sophisticated skirt design, made possible via 3-D computer modeling and CNC processing). Further taking advantage of CNC processing, all domes are CNC cut as well.
Ring placement has moved higher, with an accumulator groove featured between the top and second ring locations, which increases the volume of the area between the rings. As Barry explained, when a tight ring package is used, this accumulator groove prevents inter-ring pressure buildup, allowing both top and second rings to function properly. All ring lands are CNC-machined, and a 0.010″ radius is featured at the root of the top and second grooves (instead of a square cut), which increases material strength.
All of these new pistons also feature a silk-screen-applied Duroshield coating (moly graphite with polymer mix, which serves as an anti-friction/scuff coating), as well as lightweight tapered pins.
According to Probe’s Chris Huff, moving the rings higher produces several results, including a reduction in emissions (naturally a concern for the OE side). In racing applications, the top ring seals better when it’s closer to the top. This is good for drag or circle track applications, but if nitrous or a blower is involved, the downside is greater concern for blowing the top ring lands off. In turbo applications, for example, the rings need to move further away from the top to get away from the excess combustion heat and pressure.
Hard anodizing on the top ring groove is a solid move for high combustion temperature situations (turbo, etc.) and in some endurance NASCAR applications to prevent microwelding. However, notes Huff, “ring groove hard anodizing isn’t something we see much in the sportsman realm.”
In terms of piston compression height, according to Huff, “we’re increasingly seeing this in stroker builds where longer rods are being used, with compression heights moving well beyond the once-considered limits of 1.5 – 1.75″, to compression heights in some applications reaching the 1.2 – 1.3″ range.”
Huff also noted that in some cases, pins are moving up far enough that they intersect the oil ring groove. Huff’s advice is to stay away from this on a street engine. Instead, a slightly shorter rod coupled with an offset pin bore in the piston is a better route to take to reduce rod angle, rattle and load on the cylinder wall.
Gas porting (strategically-located holes drilled from the dome perimeter into the top ring groove) applies pressure directly to the rear ring face, basically eliminating side clearance, which prevents ring flutter during high-RPM operation. This works best with thin, narrow top rings (i.e. 0.043″ thick) and short piston compression height. However, since the positive pressure effects of gas porting tends to greatly reduce top ring life, this feature is applicable only to routinely-serviced race-only engines, and is never a good idea for a street motor.



GV………..gasket volume
DV………..below deck volume
HV………..head chamber volume
VV………, valve pocket, dome volume
(minus for dish or pockets; plus for dome)
PV…………volume displaced by piston
GV = Bore (in) x Bore (in) x 12.87 x head gasket thickness
DV = Bore (in) x Bore (in) x 12.87 x inches below deck
HV = CCs
VV = CCs
PV = Bore (in) x Bore (in) x Stroke (in) x 12.87
Compression ratio = GV + DV + HV – VV + PV
Divided by GV + DV + HV – VV

Cubic inches = Bore x Bore x Stroke x no. of cyls x 0.7854

To convert cubic inches to CCs……..Cubic inches x 16.386
To convert cubic inches to liters…….Cubic inches x 0.016386

To convert CCs to cubic inches……..CCs divided by 16.386
To convert Liters to cubic inches……Liters divided by 0.016386

Engine in Liters = Bore (mm) x Bore (mm) x stroke (mm) x no.
of cyls x 12.87,
Divided by 16386 x 1000

Engine in CCs = Bore (mm) x Bore (mm) x Stroke (mm) x no.
of cyls x 12.87,
Divided by 16386

Mahle Motorsports’ Trey McFarland noted that among the many features in their forged performance and racing piston designs are shorter pins, which enables opening up the sides of the pistons to obtain both lighter weight as well as reducing overall drag. Pin bosses are moved further inboard to work with the shorter pins. This removes flex from the pins, placing the stresses back into the piston, which allows designers to build-in the degree of strength and rigidity that’s needed to best control piston growth.
Trey also noted that all Mahle forged pistons are dip-coated with a dry film phosphate coating. The intent of this coating (a proprietary material Mahle calls Grafal) is multi-faceted. This coating maintains consistency of tolerances in the ring grooves and provides added anti-galling protection in the pin bores. Since this coating is applied to the entire piston, it prevents any potential for microwelding inside the grooves. Another very notable benefit is provided by the coating’s compressible membrane, which “cushions” the piston skirt areas. This extends piston life, generates less noise (important for fuel-injected engines that use knock sensors) and reduces piston inertia as the piston rocks, which in turn reduces shock loads and harmonics that would otherwise be transmitted to the rods and bearings.
In terms of weight reduction and increased strength, Mahle’s “box in box” underside webbing structure works in conjunction with the narrower pin bosses to increase rigidity. Trey noted that this design is sometimes not feasible in applications that use aluminum rods, as these thicker rods may not provide adequate room for this design.
Another feature involves back-cutting the ring lands between the second and third ring grooves, which allows scraped oil to more quickly and efficiently be brought down to the oil ring package for superior oil control.


Once considered a “snake oil” treatment (in reality, nothing could be further from the truth), skirt coatings have now become accepted and commonplace. This generally involves an application of moly graphite (or similar material) to the skirt surfaces. This slick coating, especially when exposed to engine oil, offers a super-slick contact area for those occasions when the skirt touches the cylinder wall (cold starts, transitional rocking at top and bottom centers). This virtually eliminates skirt scuffing, saving both the skirts and the bore surfaces. The film buildup involved in this coating is so minimal that no honing compensation is required in terms of finished bore diameter.


Dome coatings consist of thermal-barrier ceramic applications. Shown here is a ceramic coating by Swain.


Moly graphite skirt coatings offer anti-scuff protection, providing insurance against potential damage during cold starts and piton rock. Thermal dome and moly skirt coatings shown here are from Polydyne.

Thermal barrier coatings (applied to the piston dome) are generally ceramic-based materials, which serves two purposes: since the coating reflects heat (acting as a heat barrier), a much greater percentage of combustion heat is maintained in the chamber for a more efficient burn. This coating also minimizes piston thermal expansion, since less heat is transferred into the piston body. This allows greater control of, or more even, thermal expansion, theoretically permitting the use of tighter piston-to-wall clearance. These coatings, available in a variety of “grades,” are especially suited to turbocharged applications, since some of these ceramic coatings can withstand approximately 2,100 degrees F exposure.
It’s important to note that by their nature, these hard ceramic coatings MUST be applied properly. If surface prep and curing is not executed properly, this material can flake off, which will result in severe cylinder wall and bearing damage. This is why it’s critical to have these coatings applied only by an experienced and skilled coating application shop that specializes in these treatments. In other words, don’t try this at home.
While not a coating, a hard-anodizing treatment inside the top ring groove has also gained acceptance in applications where ring micro-welding is a concern.


Dial 1-800-652-0406 and then the Quik-Link
number after a company to reach them directly!


Arias Pistons
13420 S. Normandie Ave.
Gardena, CA 90249-2212
Quik-Link #11054

CP Pistons
1902 McGraw
Irvine, CA 92614
Quik-Link #11055

Diamond Racing Products
23003 Diamond Dr.
Clinton Twp., MI 48035
Quik-Link #11056

Federal-Mogul Performance
26555 Northwestern Hwy
Southfield, MI 48034
Quik-Link #11057

JE Pistons, Inc.
15312 Connector Lane
Huntington Beach, CA 92649
Quik-Link #11058

KB Performance Pistons
4909 Goni Rd.
Carson City, NV 89706-0351
Quik-Link #11059

Mahle Motorsports
270 Rutledge Rd. Unit B
Fletcher, NC 28732
Quik-Link #11060

Probe Racing Components
2555 West 237th St.
Torrance, CA 90505
Quik-Link #11061

Ross Racing Pistons
625 S. Douglas St.
El Segundo, CA 90245-4812
Quik-Link #11062

Wiseco Piston Co.
7201 Industrial Park Blvd.
Mentor, OH 44060
Quik-Link #11063

632 Mountain Motor (Part 1C)

Dart 11-Degree Big Chief Cylinder Head Specs
Material…………………355T6 aluminum alloy
Comb. Chambers……….56cc (70cc also available)
Intake valve dia…………2.470″
Intake port dim. …………1.815″ x 2.725″ w/3/4″ radius
Intake port volume………FP CNC – 497cc
Intake port location……..Raised 1.500″ spread ports
Exhaust valve dia………1.800″
Exhaust port volume……185cc
Exhaust port dim………..2.020″w x 1.780″h
Exhaust port location……angled & raised 0.900″ extended flange w/BBC bolt pattern
Intake flow………………520cfm @ 0.900″ lift/28″
SuperFlow 1020/+20cfm on SuperFlow 600
Exhaust flow…………….355cfm @ 0.900″ lift/28″
Lifter……………………..Use 0.180″ offset lifter
Manifold…………………Dart Big Chief Oval 1×4 bbl = 8″ tall
Milling…………………..56cc = 0.145″ (70cc = 0.080″)
Pistons…………………..Must use pistons for Big Chief head
Retainers………………..Titanium 10-deg
Spark plug………………0.750″ reach, gasketed Autolite AR3932
Spring cups……………..1.625″ – 0.060″ cup
Spring pockets………….1.740″ OD for 1.625″ cup (0.030″ deeper max)
Springs………………….Dart 1.625T = 330# @ 2.100″ / 0.910″ max Comp 948
Valve angles…………….Intake 11 deg x 6 deg Exhaust 7 deg x 4 deg
Valve length…………….Intake 6.600″ Exhaust 6.450″ (for 2.150″ installed height)
Valve stem dia…………..0.3415″ (11/32″) (5/16″ optional)
Valve train………………Jesel or T&D 11-deg rocker system
Valve guides…………….1/2″ OD Mag-bronze Cut for 0.500″ PC seals (0.002″ press)
Valve guide length………3.000″
Valve guide clearance……0.0014″ – 0.0021″ (with 0.3415″ dia. valve stem)
Valve guide spacing………widened for use on min. 4.600″ bore
Valve seats……………….Copper-Berylium, 0.008″ press
Valve seat dim. ………….Int 2.520″ x 2.00″ x 0.375″ Exh 2.000″ x 1.560″ x 0.375″
Valve seat angles……….. 55 deg
Head studs……………….ARP # 235-4312 (or Dart kit # 66120015)
Titanium valves………….Must use lash caps
Torque w/oil……………..Head bolts = 70 ft-lb
(Dart’s inner head studs 3/8″-7/16″ = 50 ft-lb
Manifold = 35 ft-lb
Block application………..Dart Big M, Mark IV, Gen V, Gen VI with proper head gasket
Cyl. Head weight………..42 lbs


The 0.5201 intake cam lift, when mated to our Jesel 1.85:1 rockers, will achieve an effective valve lift of about 0.962″. Lobe ramp angles are very shallow (to the eye, they look straight), so this pup should provide quite a rumpety-rump attitude.


Our roller lifters and valve springs were specially selected by Crane to suit our specific build.


This closeup shows the 0.180″ offset pushrod cup for the intake lifters, necessary for the Big Chief II 11-degree heads.


Our rocker system is a shaft roller setup from Jesel, featuring a hefty 1.85:1 ratio. Along with our custom Crane cam, this will provide nearly an inch of effective valve lift. Woof.


Our head gasket choice are MLS units from Victor.


Tri-Armor main and rod bearings from Clevite will create the necessary oil film to support our crank and rods. This is Clevite’s new line of coated bearings. The coating applied by Clevite is a proprietary polymer-based compound.


The Moroso billet gerotor style oil pump is a kick-ass unit with a built-in pickup screen, so there’s no worry about vibrating or cracking a pickup tube.


Here’s a closeup of the oil pump’s built-in pickup screen.


We opted for a Jesel belt drive for precision cam rotation.


We selected an 8″ ATI Super Damper to jive with our MSD flying magnet ignition system.


The Moroso wet sump aluminum oil pan is a recent addition to their line. The pan rail configuration requires extra tapped holes in the block’s rails.


Threaded plugs in the pan allow driver access to the center rail fasteners.


Moroso sheet metal aluminum valve covers will adorn the Dart Big Chief II heads.


The MSD Pro Billet distributor features a length that will accommodate the Dart tall-deck block.


The MSD flying magnet crank trigger will provide accurate ignition timing (this requires the use of an 8″ damper).


MSD Super Conductor plug wires are 8.5mm thick for carrying ample juice to this radical pup.


In order to take advantage of maximum coolant flow, and to eliminate the need for a water pump belt, we chose an electric pump from Meziere. This unit features a chrome finish, but black (and other colors) is also available.


Our giant-gulp carb is Holley’s 1150 cfm Dominator. This will be used if we opt for a single-carb intake manifold.


Depending on our intake manifold choice, we may run a pair of 1050s.


ARP threaded fasteners will be used throughout to anchor everything together. We opted for head studs instead of bolts.

Product Support
Thanks to the following for their involvement in this project…

Dial 1-800-652-0406 and then the Quik-Link number after a company to reach them directly!

1863 Eastman Ave.
Ventura, CA 93003
Quik-Link #11064

6747 Whitestone Rd.
Baltimore, MD 21207
Quik-Link #11065

1350 Eisenhower Place
Ann Arbor, MI 48108-3282
Quik-Link #11066

530 Fentress Blvd.
Daytona Beach,FL
Quik-Link #11067

353 Oliver St.
Troy, MI 48084
Quik-Link #11068

23003 Diamond Dr.
Clinton Twp, MI 48035
Quik-Link #11056
1801 Russellville Rd.
Bowling Green, KY 42101
Quik-Link #11069

1985 Cedarbridge Ave.
Lakewood, NJ 08701
Quik-Link #11070

(see Holley Performance Products)
Quik-Link #11071

270 Rutledge Rd., Unit B
Fletcher, NC 28732
Quik-Link #11060

80 Carter Dr.
Guilford, CT 06437
Quik-Link #11072

1490 Henry Brennan Dr.
El Paso, TX 79936-6805
Quik-Link #11073

632 Mountain Motor (Part 1B)

Dart’s new monster big block offers a choice between 10.600″ or 11.100″ deck heights, a cam tunnel that’s moved up 0.600″ for better connecting rod clearance with stroker cranks and a choice between 4.840″ or 4.900″ bore spacing. The new tall-deck block offers engine builders great versatility with variable lifter locations and provisions for symmetrical or siamesed-port cylinder heads.
To avoid pump pickup cracking (due to engine shake), we opted for a very beefy billet gerotor style oil pump from Moroso, their P/N 22167. This pump features a built-in pickup incorporated into the bottom of the billet pump body, so there’s no external pickup to vibrate loose. The matching oil pan to accommodate the Dart block and this pump is Moroso’s billet 2-piece aluminum pan, P/N 20376.
Crane was kind enough to machine a custom-grind steel billet solid-roller stick for us. This is P/N 13R001027, Grind number R-288/5201-2S-14 SFO (Special Firing Order). Effective lift (with our raunchy 1.85:1 rocker ratio) is almost a full inch…woof!
@ cam….. 0.5201″ intake; 0.5001″ exhaust
(with our 1.85:1 rocker ratio from Jesel, valve lift should be 0.962″ intake and 0.925″ exhaust. If used with 1.70:1 rockers, valve lift would be 0.884″ intake and 0.850″ exhaust)

317.0 deg. intake; 356.0 deg. exhaust
Intake 0.020″; Exhaust 0.022″
CAM TIMING (@ 0.020″ tappet lift)
Intake opens 49.5 deg. BTDC; closes 87.5 deg. ABDC
Exhaust opens 113.0 deg. BBDC; closes 63.0 deg. ATDC
CAM TIMING (@ 0.050″ tappet lift)
Intake opens 35.0 deg. BTDC; closes 73.0 deg. ABDC
Exhaust opens 96.0 deg. BBDC; closes 38.0 deg. ATDC
Duration: Intake 288.0; exhaust 314.0
VALVE SPRINGS (P/N 96849 triples)
Closed 352 lbs @ 2.200″
Open 928 lbs @ 1.370″
(minimum RPM 4700; maximum RPM 8700; valve float 9300 RPM)
NOTE: This is a special firing order (SFO) camshaft.
Firing order is 1-8-7-3-6-5-4-2
As usual, we’ll provide plenty of detailed information relative to all of the components as well as all machining and assembly info in the next article.
As I mentioned earlier, Diamond is making our forged pistons (they have plenty of experience in designing slugs for 632 builds, so this’ll work out peachy). In the next issue, I’ll provide all of the custom piston specifications.
As soon as Eric Simone of Diamond Racing finishes our pistons, we’ll hone-fit the cylinders and file-fit our Perfect Circle rings. At that point, we’ll fit-check our crank and rods for clearance. Once that’s done, we’ll balance the crank, rods and pistons and begin our trial-fit, degreeing the cam and measuring for pushrod length. We expect to perform a host of fitting procedures, including fine-fitting and port-matching our intake manifold-to-head fit, checking pushrod clearance and correcting as needed, etc.
Oh, by the way, we plan to use a new digital cam degreeing system from Cam Logic, which we’ll feature in depth. I saw this at the recent PRI show in Orlando, and it made my mouth water (I wanted to use a different analogy, but I need to watch my language). I can’t wait to try it out.
While we won’t pursue a perfect smooth exterior block finish (remember our recent 383 Dart smallblock Chevy streetrod build?), we’ll nonetheless tidy up the block exterior for enhanced appearance, eliminating any casting flash. We haven’t decided on a block color yet, but I think we’ll stay away from black, mainly because it’s difficult to photograph (black hides too many details).
Once our mutant baby is final-assembled, we’ll trek up to Koffell’s Place in Huron, Ohio for the dyno run, using Scott’s DTS engine dyno. If all goes well, we should be able to comfortably nudge around 1200 HP out of this big-gulper.


Our Dart Big M block features a 10.2″ deck height (9.8″ deck is also available). Camshaft bore position matches standard big block Chevy.


Bores are slightly undersized, providing plenty of meat to hog out to achieve our 4.600″ desired diameter. Minimum cylinder wall thickness is 0.300″.


The steel billet main caps feature splayed outer bolts on #2, 3 and 4 (all caps are 4-bolt), and feature deep-stepped registers on each side. The main bearing bore measures 2.937-2.938″, accepting standard big block Chevy main bearings.


Lifter bore diameters measure 0.8427-0.8437″, accepting +0.300″ longer roller lifters.


Each valley side of the block features two slotted bosses to accommodate the four head bolts that are installed on the underside of the heads.


Clearance reliefs are already provided at the bottom of the bores. Depending on the stroke, additional clearancing may be required. We’ll test-fit our 4.750″ stroker crank to verify.


The Dart Big Chief II alloy heads are, well, big. This is a hefty 42-lb chunk of 355T6 aluminum.


Intake flow is rated at 520 cfm @ 0.900″ lift at 28 inches on a SuperFlow 600 test bench. Intake port volume is 497cc.


Our heads feature 56cc chambers (70cc also available). Intake valve diameter is a whopping 2.470″, and exhaust valves are 1.800″. The heads came equipped with Victory titanium valves.


Intake ports are 2.725″ x 1.815″ and feature a 3/4″ radius.


Exhaust ports (as intakes) are CNC machined. Notice the beautiful blend radius at the valve boss.


This says it all.


Our crank is a steel unit from Lunati, with 4.75″ stroke.

That’s a hefty stroke in anybody’s language.


Our rods are Lunati Pro Billet I-beam connecting rods, P/N LB01.


The Lunati rods feature a center to center length of 6.700″.


The matching Crane set includes cam, offset roller lifters, springs, retainers and locks.


Our bumpstick is a steel billet cutie from Crane. We’re also using their solid roller lifters (offset to work with the Dart heads), titanium keepers and retainers, and big-ass springs (rated for float at 9300 RPM).

632 Mountain Motor (Part 1A)

We build a big, big block drag mill

just for the sheer hell of it.

by Mike Mavrigian

photos by author


Some folks love to claim that bigger is not always better. While that may be true in some cases, let’s face it…when the conversation turns to displacement, well, bigger cain’t never hurt. After all, if you feed any block huge doses of Viagra, rest assured that you’ll be able to sit back and enjoy the show.
We’ve talked to a few builders who have produced 632 CID all-motor drag engines, and generally speaking, they’re popping around 1,200+ HP out of these big-breathers. So, we figured we might as well build one and provide our readers with all of the pertinent details. Sure, there are larger-cube mills out there, but the popular 632 sounds like a neat build, so that’s what we chose.
The basis of our build will begin with a stout no-nonsense Dart “Big M” iron block that features a 10.2″ deck height. We’ll hog the bores to 4.600″, and mate this to a whopping 4.75″ stroker crank from Lunati. We plan compression on the tight-squeeze side, at about 15:1. No laughing gas or added air-squeeze for this bad boy…it’s gonna pop, dig in it’s hoofs, and bellow and scream by simply igniting the fuel and air fed through either a single 1150 cfm Holley Dominator or a pair of Dominator 1050 carbs, depending on our intake manifold of choice. We’ll mechanically feed fuel to the carbs via -8 plumbing.
We’ve gathered most of the parts needed with the exception of the forged & CNC-cut pistons, which are being custom made by Diamond Racing Products. We discussed our piston specs with Diamond’s Eric Simone, who was a tremendous help in determining the piston configurations based on our specific build. Piston rings are coming from Clevite/Perfect Circle. Top rings will be ductile iron with plasma face, with an axial height of 0.043″ and radial width of 0.170″. Second rings will be gray iron THG with axial height of 0.043″ and radial width of 0.210″. These rings will be file-to-fit. The oil ring package will feature an axial height of 3mm and a radial package width of 0.146″.
Once we perform our initial test-assembly, we’ll order a set of custom-length pushrods (likely 7/16″ diameter). We thought our readers would be interested in reviewing our plans to date. This build should be both informative and fun (hey…fun is always good).

Our Parts List
BLOCK………………………….Dart Big M with 10.2″ deck height
CYLINDER HEADS……………Dart Big Chief II 11-degree with 56cc chambers
CRANKSHAFT…………………Forged 4.75″ stroker from Lunati, P/N BS-421 MN
(counterweight radius @ 3.700″)
CONNECTING RODS………….Forged I-beam Pro Mod 6.700″ Lunati, P/N LB01
CAMSHAFT…………………….Custom billet steel mechanical roller from Crane,
P/N13-R001027; grind no. R-288/5201-2S-14 SFO
LIFTERS…………………………Crane offset solid roller Ultra Pro R/T rollers P/N 13571-16
RETAINERS/KEEPERS………..Crane titanium set P/N 99681-16
VALVE SPRINGS………………Crane triple spring set P/N 96848-16
MAIN BEARINGS………………Clevite Tri-Armor P/N MS-829 HXK
ROD BEARINGS………………..Clevite Tri-Armor P/N CB-743 HXK
OIL PUMP……………………….Moroso billet gerotor P/N 22167
OIL PAN…………………………Moroso 2-pc welded billet aluminum, P/N 20376

CARBURETOR…………………Holley Ultra Dominator 1150 cfm, P/N 0-80673
INTAKE MANIFOLD…………..Profiler tunnel ram
TIMING/COVER………………..Jesel belt drive kit KBD-32000

VALVE COVERS……………….Moroso welded aluminum P/N 68334
ROCKER ASSEMBLIES………..Jesel shaft roller rocker system P/N KPS 24347
(1.85:1 int & exh)
PISTONS…………………………Diamond Racing
DISTRIBUTOR…………………..MSD billet, P/N 8558 (tall block)
CRANK TRIGGER………………MSD flying magnet kit P/N 8620
DIST. CLAMP……………………MSD P/N 8110
SPARK PLUG WIRES……………MSD 8.5mm Super Conductor P/N 31239
WATER PUMP……………………Mezier WP300
DAMPER………………………….ATI 8″ Super Damper P/N 917062
CYL. HEAD GASKETS…………..Victor MLS P/N 54271
THERM. HOUSING GASKET…….Victor (alum. W/silicone seal) P/N C21331
REAR MAIN SEAL………………..Victor 2-pc P/N JV705
EXH. GASKETS……………………Victor Nitroseal Pro-Stock P/N 95178SG
Head studs # 235-4312
Header studs # 400-1403
Oil pan studs # 435-1901
Balancer bolt # 235-2501
Carb stud kit #400-2414
Intake manifold bolt kit # 435-2101
Timing cover bolt kit #400-1501
Thermostat housing bolt kit # 430-7401
Flexplate bolt kit # 200-2902
Valve cover stud kit # 400-7615
Distributor stud kit # 430-1701
Water pump bolt kit # 430-3201
ARP moly assembly lube # 100-9906

Part No. ……………….31263344 through 31273454
Material…………………superior iron alloy
Bore…………………….4.250″ and 4.500″
Bore & stroke…………..4.625″ x 4.750″ max recommended
Cubic inch………………632 CID max recommended
Cam bearing bore ID……2.1195″ – 2.1205″
Cam bearings……………Special coated, grooved, w/ 3 oil holes
Cam bearing O/S………..+0.010″, +0.020″, +0.030″
Cam bearing press………0.002″
Camshaft position………standard BBC
Cam drive………………standard timing chain, gear drive or belt drive
Cam plug……………….standard BBC 2.218″ dia.
Cylinder wall thickness…0.300″ minimum @ 4.625″ bore
Deck height……………..9.800″ & 10.200″
Deck thickness………….adequate for all applications
Fuel pump………………mechanical pump provision
Fuel pump pushrod……..standard BBC
Freeze plugs…………….press-in cup plugs
Head gasket…………….Fel-Pro #1037, 1047 or 1067
Inner head stud………….2 slotted bosses per side
Lifter bores……………..BBC 0.8427″ – 0.8437″
Lifter galley……………..raised 0.350″ for longer lifter bore
Lifter type………………roller Gen VI (+0.300″ longer), solid Mark IV
Main bearing size………standard BBC
Main bearing bore………2.937″ – 2.938″
Main caps……………….steel billet or ductile iron (sportsman); all 4-bolt
Main cap register……….deep-stepped register on each side (no need for dowels)
Main cap press………….0.005″
Main cap bolts…………..all 1/2″ (#2, 3, 4 have splayed outer bolts)
Oil system……………….wet or dry sump, main priority oiling
Oil galley, main………….stepped, 9/16″ – 1/2″ – 7/16″
Oil galley, filter main……5/8″
Oil filter………………….stock oil filter location
Oil pan……………………standard pan bolt pattern,
extra bolt holes provided for strokers
Rear main seal……………standard 2-pc seal / Fel-Pro #2918
Rear main thrust width…… 1.622″ – 1.624″
Serial number……………..on main caps
Starter……………………..mounts in standard location
Stud holes, head……………blind holes
Timing chain/gears………..standard BBC
Timing cover………………standard BBC
Torque specs………………all 1/2″ bolts @ 100 ft-lbs
Weight……………………..4.250″ bore = 280 lbs
4.500″ bore = 260 lbs
4.600″ bore = 250 lbs

-AN Hose and -AN Hardware (Part 5)

While I’m on the subject, here’s a very cool specialty tool that eases the pain of hose assembly. I just came across this tool recently, and I like it. It’s called the Koul Tool (aptly named). While you don’t absolutely need this tool, if you want to save your fingertips from needle punctures from frayed stainless-steel wire, I’d highly recommend it.
The tool is essentially a guide that allows you to feed the hose onto the hose end’s collar, while encapsulating the sharp tips of the wire braid.
The tool is offered in kit form, to cover all popular hose sizes. Kit P/N 468 covers sizes -4, -6 and -8; while Kit P/N 1016 covers hose sizes -10, -12 and -16.
Here’s how it works: Choose the correct-size tool for the hose end to be installed. The tool is made of two pieces that clam-shell together. Place the hose end collar in one side of the tool, enclose it with the mating side, secure the tool in a vise, lube the funnel entrance and install the hose using a twisting motion. The tool’s funnel entrance guides the hose neatly into the collar with no muss or fuss.
In fact, while the hose end cap is still in the clamshell, with the hose inserted, you can leave the tool in the vise and install the remainder of the hose end, threading it into the collar while the collar is held stationary.
The kits include several adapters, since the various hose end and fitting makers often produce their own unique lengths. The kit instructions advise you regarding the need for adapter spacers. For instance, the kit’s #1 adapter is required for Aeroquip -16, while -16 Fragola, Goodridge, Earls and XRP hose ends require the kit’s #2 adapter. The hose end must fit inside the tool tightly, with no end-play. The adapters simply serve as spacers to prevent the hose end from walking inside the tool.


These are the hose-end installation tools from Koul Tool. Two kits are available. The kit on the left handles sizes -4, -6 and -8, while the kit on the right handles sizes -10, -12 and -16.


Simply place the hose end collar into one half of the clamshell tool, with the hose entry port facing the tool’s funnel end.


Assemble the two clamshell halves together.


Lube the funnel port, and insert the braided hose, “screwing” the hose into the tool in a clockwise movement. You’ll feel the hose stop against the collar threads.


With one half of the clamshell removed, you can see the hose installed into the collar. This is a very “slick” (pun intended) way to install a braided hose into a collar.
Note: because some maker’s hose end collars vary in length, the Koul Tool kits include plastic spacers and instructions regarding the need for a spacer (and spacer size), depending on the specific brand of hose end being assembled. If a spacer is needed, it is positioned between the collar’s threaded port (the hex side) and the inside of the tool. If a certain hose-end maker’s collar is on the short side, as it is pushed back into the tool during hose insertion, the hose entry port might move back behind the funnel port, possibly allowing the hose braid to expand. The object is to place the hose end collar’s hose port directly at the base of the tool’s funnel. This isn’t difficult. The tool instructions clearly tell you when a spacer is needed, so there’s no need for you to figure anything out. Here we used an Aeroquip -10 hose end collar, where no spacer was required.

As long as the hose and collar are in the tool, you can take advantage of this and insert the hose end socket/nipple. Here, we removed the hose and tool from the vise and flipped it 180 degrees to expose the collar’s threaded port. Remember to lube the nipple and threads.


Here we tighten the hose end assembly using an aluminum -AN wrench.


Each Koul Tool is clearly marked for -AN size.


Even for seasoned racers who have assembled countless numbers of -AN hose ends, this little tool is, well, way cool. It’s like using a good shoehorn. It definitely saves your fingers.

Whenever you’re dealing with aluminum hose ends and fittings, be aware of two precautions: aluminum is softer than steel, so your steel tools can gouge or burr these items. Also, if you’re concerned about appearance (street rod, custom application, etc.), you certainly don’t want to burnish off the attractive anodized finish. Instead of taping a wrench or trying to jam a piece of cloth between the fitting and a wrench, make the investment and buy a selection of aluminum -AN wrenches. The aluminum wrenches, unless they’re dirty and gritty, won’t damage your pretty hose ends or fittings.
Also, be aware that an anodized component’s finish can be damaged by aggressive solvents. You can damage the coloration by using some brake cleaner solvents or thinners. However, some anodized items feature a protective clear anodizing treatment over the color-dyed treatment that helps to protect the appearance. Regardless, don’t take chances. Use only a mild cleaner, and never use any cleaner that contains abrasives (such as buffing compound).


If you care about preserving the appearance of your aluminum hose ends and fittings, invest in a set (or two) of aluminum AN wrenches. The set shown here is from Gearhead Tools, but this type of wrench is readily available from most of the hose/hose end makers. Believe me, you need these tools!


Even when using an aluminum AN wrench, make sure that the surfaces are clean to prevent scratches that could result from grit. Here we install hose assemblies onto a race engine’s dry sump pump.


AN wrenches are clearly marked for the intended AN size, plus they’re usually color-coded per size to make it easy to identify them. Notice the small radiused cutouts at the corners on this wrench, which prevents corner-edge contact. If a bit of dirt has accumulated in the corners, these cutouts help keep grit away from the hose end.


Although aluminum AN wrenches are designed for this dedicated task, bear in mind that not all hose end and fitting hex dimensions are created equal, as some hose end and fitting manufacturers’ hex dimensions may differ. However, these wrenches will fit the vast majority of applications as intended. The fit of this -12 wrench on this XRP -12 hose end is perfect.


Stainless braided hose and AN hardware provides worry-free hose life (don’t need to worry about a hose leaking due to a rub-through) and reliable connections, since the 37-degree AN seating creates a surefire fluid seal.


Considering the many possible combinations of hose end and fitting angle shapes available, it’s easy to obtain exactly the routing that best suits your needs and visual tastes.

If you opt to use AN hose ends with barbed nipples and the proper reinforced hose designed for these hose ends, in theory the task is easy. Simply insert the barbed nipple tube into the hose until the end of the hose seats into the shallow stop-collar. However, this is anything but easy, due to the tight interference fit of the nipple in the hose. Lube the nipple with WD40 or lithium grease, and push the hose onto the nipple. You’ll need your strength for this. I’ve found that it helps to first dip the end of the hose into very hot water (to slightly soften and expand the hose). Once the hose is fully inserted, it’s not coming off.


Reinforced hose designed for use with barbed nipple hose ends. This is tough stuff. You’ll need a very sharp razor to cut this.


Shown here is a 90-degree barbed-nipple AN hose end. The two barbs provide an extremely secure retainment to the hose.


Here the hose is pushed onto the nipple about halfway. Keep working with it until the end of the hose seats fully into the shallow stop-collar.

Quick-connect/disconnect fittings are available that allow you to quickly (with no tools) disconnect or connect fluid hose assemblies with no fluid loss. Jiffy-Tite (probably the most popular of this genre) offers self-sealing connectors suitable for fuel, oil and water applications. The coupler features a spring-loaded valve that shuts off when the coupler is disconnected, and opens when connected. This is perfect for race cars, where engines are serviced or changed on a regular basis, since this quick-connect feature saves time. Simply slide the coupler collar back to release the connection. You can pop the couplers loose and yank an engine without spilling fluids. Even though these couplers are easy to disconnect and reconnect by hand, once coupled, the connection is secure with no worries about accidental disconnection or leakage.
These self-sealing fittings are available in a variety of thread styles including AN, NPT pipe thread, reusable hose ends and barb type hose ends. Every imaginable configuration is also available (male/male, male/female, female/female, etc.).

Straight hose end (left) with self-sealing quick-disconnect coupler. This connects to the coupler fitting (right), which in turn features a male -AN flare. Photo courtesy Jiffy-Tite

Special quick-connect carburetor adapters are available (installed at the carb bowl as seen here) that accept the quick-connect hose end. This allows you to pull the spring-loaded coupler back, and disconnect the fuel line from the carb with no fuel loss, since the hose end seals itself when uncoupled. Photo courtesy Jiffy-Tite


This dry sump oil system connects to its remote oil reservoir using a Jiffy-Tite quick-connect hose end coupler. This particular engine is on a display stand, but in a race car, this allows you to quickly disconnect the oil hoses without spilling oil. As soon as the coupler is disconnected, a spring-loaded valve shuts and seals.

This quick-connect coupler features a male -AN (where it mates to the 90-degree hose end).


Jiffy-Tite offers a wide range of configurations. Pictured here is a 45-degree hose end that features the self-sealing quick-connect coupler. Photo courtesy Jiffy-Tite


Pictured here is a 90-degree quick-connect hose end. Photo courtesy Jiffy-Tite

-AN plumbing can also be handled using hard-line tubing. -AN flare-seat connections are made using tube sleeves and tube nuts. We don’t have room in this article to address tubing in detail, so we’ll try to present a separate article in tubing in a future issue.

This custom Chevy smallblock, intended for a street rod build, is adorned with hard-line fuel plumbing. I had a specific theme in mind when I built this engine, and decided that hard lines would look nifty. I sent all of the aluminum tube nuts, tube sleeves and AN adapters to a custom anodizing shop where they were stripped of their original blue color and re-anodized in a dark violet color to contrast with the lavender metallic engine color. We hand-polished the 3/8″ aluminum tubing.

This hard-tube plumbing setup on a Honda engine shows what can be done with a simple hand-held tubing bender and a little bit of patience.

Dial 1-800-652-0406 and then the Quik-Link number after a company to reach them directly!

(reinforced hose, hose ends, fittings)
1927-2 Stout Dr.
Warminster, PA 18974
Quik-Link #11074

(reinforced hose, hose ends, fittings, adapters)
14615 Lone Oak Rd.
Eden Prairie, MN 55344
Quik-Link #11075

(reinforced hose, hose ends, fittings, adapters)
Concord, NC
Quik-Link #11076

(braided brake hose assemblies)
1470 Amherst Rd.
Knoxville, TN 37909
Quik-Link #11077

(reinforced hose, hose ends, fittings, adapters, coolers)
Holley Performance Products
P.O. Box 10360
Bowling Green, KY 42102
Quik-Link #11078

302 Gasoline Alley
Indianapolis, IN 46222-3967
Quik-Link #11079

(reinforced hose, hose ends, fittings, adapters)
888 W. Queen St.
Southington, CT 06489
Quik-Link #11080

(aluminum AN wrenches)
P.O. Box 21887
Carson City, NV 89721
Quik-Link #11081

(reinforced hose, hose ends, fittings, adapters)
529 Van Ness
Torrance, CA 90501
Quik-Link #11082

(fittings, quick-connect fittings)
4437 Walden Ave.
Lancaster, NY 14086
Quik-Link #11083

(braided hose assembly tool)
405 Jones Dr.
Lake Havasu City, AZ 86406
Quik-Link #11084

(reinforced hose, hose ends, fittings, adapters)
P.O. Box 2936
Torrance, CA 90509
Quik-Link #11085

(reinforced hose, hose ends, fittings, adapters)
5630 Imperial Hwy
South Gate, CA 90280
Quik-Link #11086

-AN Hose and -AN Hardware (Part 4)

With NPT threads, simply apply Teflon sealing tape or compound. However, when using an AN adapter that features straight thread at one end, you need a sealing washer. Depending on the applications, you’ll need either an O-ring or a crush washer. O-rings are available in both Buna N synthetic rubber and in Viton. Buna is compatible with most fuels, hydraulic fluids and lubricants up to about 275 degrees F. Viton is preferred for synthetic lubricants, oxygen-bearing fuels and additives and non-ether-based brake fluids. Viton also offers better scuff resistance, longer service life and offers a higher operating temperature range of about 400 degrees F.
Crush washers do exactly that….they crush under compression, providing the needed seal between two flat surfaces, where there is no groove relief to accept an O-ring. Crush washers are commonly available in aluminum and copper. Banjo fittings, for example (as used on brake line connections to calipers) require two crush washers…one between the banjo fitting and the caliper, and one between the banjo fitting and banjo bolt head.
Crush washers MUST match the inside diameter of the adapter. Whether you’re dealing with aluminum or copper, it is highly recommended to never re-use old crush washers. Always replace with new, since once they’re crushed, they don’t “spring back” to their original thickness, and the “fingerprint” will have mirrored the parent surface of the original installation, and might not seal against a different surface.
Crush washers are generally available in hole diameters including 3/8″, 1/2″, 10mm, 12mm, 7/16″ and 9/16″.
Another…and better approach to sealing banjo assemblies are aluminum washers with built-in rubber O-rings. This approach offers the best of both worlds…the strength and crush of aluminum, plus an O-ring that expands to provide a superior seal. This type of sealing washer is available in two basic formats (one is of American design and the other was born in England). The American design, called the Stat-O-Seal, features a synthetic rubber O-ring captured (mechanically locked) inside the I.D. of an aluminum washer. This is a great choice to seal anything that normally would use an aluminum or copper crush washer.
The English-origin version is called the Dowty seal, which is similar to the Stat-O-Seal, but the O.D. is smaller and the washer is thicker. Either works well, but the Stat-O-Seal is more readily available.
As an example of the superior sealing offered by a Stat-O-Seal, I recently reconfigured the front brakes of a 1973 Duster (fitted with a non-original 426 Hemi) to disc brakes. The owner wanted an “OE” look, so I chose single-piston cast iron calipers from a well-known caliper remanufacturer. I initially installed copper crush washers at the banjo fittings, but could not achieve a seal (constant wetness). I tried different-thickness copper crush washers, and even tried aluminum crush washers, but to no avail. Further inspection showed that the sealing seats on the calipers (where the crush washer was position between the caliper seat and the banjo fitting) were never re-faced after the caliper bodies were blasted during cleanup. The sealing seat surface was irregular (not milled). I exchanged the calipers for replacements, but got the same pitiful results. Finally, I replaced the crush washers with Stat-O-Seals. Guess what? Instant perfect seal. No leaks, no more cussing and no more re-bleeding.


O-rings are available in either BUNA N or VITON.

Aluminum crush washers.

Stat-O-Seals. These feature synthetic rubber O-rings captured inside aluminum washer shells. These buggers work great.

Dowty seals. These sealing washers are of British origin. They feature a smaller-O.D. and a thicker cross-section than Stat-O-Seals, but essentially work the same way, with an O-ring inside an aluminum housing.

While we’re on the subject of sealing fluid, here’s something many people aren’t aware of: If you have a damaged AN 37-degree sealing surface (hose end of adapter) that may have been caused by galling when assembled dirty, etc., you can make a quick and easy field-fix without the need to replace the hose end or adapter. Aluminum conical seals are available in all AN sizes. This is simply a small, shallow conical “cup” that matches male and female seat angles. Simply push the conical seal over the male cone and reassemble the hose end to the adapter in the normal manner.


Conical seals offer a quick field-fix for damaged 37-degree AN hose end-to-adapter connections.

NOTE: -3 and -4 sizes are relatively small in diameter. Especially for brake hose applications, these are very difficult to assemble by hand and often require crimped hose ends. For brake lines, or high-pressure hydraulic clutch hoses, don’t try to make your own. Buy brake hoses or clutch hoses already assembled in the lengths you need.
The following instructions apply only to stainless steel braided hose and appropriate hose ends. Crimp-type hose ends require special crimping dies, available from the hose maker. Dedicated hydraulic crimping machines are also available and come in handy, especially if you plan to assemble a bunch. Slip-on hoses and barbed nipples are self-explanatory. Simply “slip” the hose over the barbed nipple. Be aware that this isn’t as easy as it sounds, since the fit will be very tight. Eat your Wheaties before tackling slip-ons.

When you buy a length of -AN stainless-steel braided hose and plan to cut pieces to desired length and make your own assemblies, you first need to know how to properly cut the hose.
Yes, you can use a hacksaw, but frankly, that method stinks. It’s difficult to obtain a square cut. To do so, you need to use a special hardened blade, and chances are very high that you’ll end up with frayed wire ends that you’ll then need to snip off with wire cutters (by the way, snipping this hard stainless wire braid isn’t as easy as it may seem). If you secure the hose in a vise to make your cut, you’ll have a tendency to smash the hose out of round, which will only aggravate the problem.
The best method is to use an abrasive “chop saw.” First, wrap the area to be cut with electrical tape or a quality bodyshop masking tape (wrap the hose tightly). Mark your intended cut on the tape, carefully cinch the hose in the saw’s vise without distorting it, and let the abrasive wheel slice through. Don’t apply a bunch of pressure on the saw arm. Light to moderate pressure works best.
Once the cut is made, remove the tape and thoroughly rinse the hose out using compressed air to remove all wire and rubber particles. This is important! Make sure the hose is clean inside. Naturally, you must always wear eye protection when cutting hose, when trimming stainless braid or when blowing hose clean.


Mark the hose at the cut location. Body masking tape works well not only as a background for marking, but to help retain the stainless steel braid ends once the hose is cut.


An electric “chop saw” fitted with an abrasive cutting wheel works well for cutting stainless-steel braided hose.


Position the hose on the saw, making sure that the saw clamp is adjusted for a 90-degree cut. Avoid cutting the hose at an angle.


Allow the saw wheel to gain full speed before contacting it to the hose. Maintain steady, moderate pressure. Don’t push so hard as to deform the hose.


This is exactly what you don’t want. This is what happens when someone tries to cut stainless-steel braided hose with a dull hacksaw, with “snips” or by cutting the hose without wrapping the cut area with tape. This cut is useless. Don’t even attempt to install a sloppy hose like this onto a hose end. If you start to snip the frayed ends with metal snips, you’ll just end up making more of a mess. If you have a cut like this, simply start over.

This hose was cut on the abrasive wheel chop saw. Once the cut is made, be sure to blow the hose out with compressed air to remove bits of rubber and braid. We lightly secured this hose in a vise only for the photo.


If you plan to assemble -AN hose ends, buy a pair of these soft aluminum vise jaws. You can secure aluminum hose ends or adapters in these jaws without damaging the material. If you keep the jaws clean, you can also eliminate surface scratches on the anodized pieces. The jaws feature female V-cuts that accept the hex of the hose end or adapter, in either horizontal or vertical planes, as you wish.


The backside of the soft jaws feature a step (this locates the jaw onto the top surface of the vise jaw) and a magnet, which holds the aluminum jaw to the vise.


A pair of soft jaws installed on a vise. These jaws will come in handy for plenty of non-related future fab work as well, such as whenever you need to secure a piece of aluminum round bar stock, etc.


Here we insert a stainless-steel braided hose into a hose end collar. There are many ways to go about this. Often, I simply screw the hose end collar onto the hose by hand. We’re simply showing the collar in a vise for illustration. However you approach this, be careful of the braids at the cut end. If you’re going to draw blood, this is when it’s gonna happen.


Push/twist the hose into the hose end socket roughly 1/8″ to 3/16″ short of the threaded area.


Check to make sure that the hose is fully seated in the hose end socket. Don’t push the hose into the threaded area If the hose (and its stainless-steel braid) enters the threads, they can jam between the male and female threads when the hose end is assembled.


The section of the hose end that features the metal sleeve threads into the hose end’s socket. Apply a bit of lube to the sleeve and to the threads to aid assembly and to prevent galling. A light lubricant such as WD-40 or lithium grease works fine.


A 45-degree hose end shown here before being fully tightened. The hose end’s socket (attached to the hose) can be secured in an aluminum vise jaw, while the hex on the hose end’s threaded collar is tightened. Note that some hose ends are designed to rotate, while others are designed to retain a fixed position once tightened. If the hose end is not designed for rotation after it’s assembled, make sure that the angle aligns with your intended fitting once installed.


Once the hose end collar is installed, I like to place a piece of tape on the hose, flush to the base of the collar. This provides a visual reference so you will still be able to tell if the hose begins to pull out of the collar during the rest of the hose end assembly.


Here, the hose end collar is secured in aluminum soft jaws on the vise. There’s no need to tighten the living daylights out of the jaws. Just snug the jaws to prevent the collar from moving.


Apply a bit of lube to the hose end’s nipple and threads.


Insert the hose end’s tube into the collar, being careful to center the nipple to the hose I.D. If you try to insert the nipple off-center, you can force the nipple edge into the hose rubber, damaging the hose. Take your time. You’ll be able to feel the nipple entering the hose.


Continue to insert the nipple until you can engage the threads. Make sure the threads are not crossed. Tighten as far as you can with your fingers, verifying that thread engagement feels/looks good.


If you care about the finish of your hose end, use a clean aluminum -AN wrench to tighten the hose end assembly. Here we’re using a -10 wrench, which fits our -10 hose end.


Continue to tighten the socket/tube into the collar, using moderate pressure. Do not overtighten! Remember: These are aluminum parts. Also, as you tighten, the nipple seals into the hose I.D., creating a leak-proof connection. Note: it’s a good idea to apply a bit of a push of the hose towards the collar during tightening just to make sure the hose isn’t pushed out of the collar. Again, observe your reference tape.

You’ll know the assembly is fully tightened when it stops or offers too much resistance. This narrow nut is almost touching the collar.


Blow with compressed air again. Once a hose is fully assembled, I like to run hot soapy water through it, followed by compressed air, followed by air-drying. Do everything you can to make sure the hose is clean inside. I know plenty of guys who gripe about clogged carburetor jets or stuck needles and seats when it’s their own fault because they didn’t take the time to inspect and clean new hose assemblies before installing them.


Hose end fully installed onto a braided hose. Note that the reference tape only moved about 0.020″, which is fine. Using the tape helps. If the hose walked out noticeably, the hose end socket/nipple must be removed, the hose repositioned and re-assembled.

-AN Hose and -AN Hardware (Part 3)

(Unique adapters for special applications)

90-degree dash AN male to straight-thread male (note sealing O-ring on straight thread).
This adapter features swivel for rotation of male AN.


90-degree dash AN female to NPT male swivel.

90-degree dash AN male to dash AN female swivel.


90-degree dash AN female to dash AN female swivel.

90-degree dash AN female to dash AN female swivel, low profile.


45-degree dash AN male to dash AN female swivel.

45-degree dash AN female to dash AN female swivel.


45-degree dash AN female to dash AN female swivel.

Dash AN female to tubing adapter. This allows connection between flexible AN hose to a tube. The tube side seals on a compression fitting.

Dash AN female to dash AN male reducer.

Dash AN T female swivel on run. All three connections are dash AN (featuring 37-degree cone seating). This version features two male AN and one female AN, all the same size.

Dash AN T female swivel on branch. This adapter features three same-size AN connections, with two males on the main run and one female at the branch.


Straight AN female swivel coupling. Same size female AN at each end. The two halves swivel.

Straight dash AN female to female reducer swivel coupling. This adapter features two female AN fittings of two different sizes. For example, allowing connection of a -8 AN to a -6 AN.

Straight dash AN female to NPT male swivel adapter.

Extended straight male AN to straight thread. The example shown here features a male -8 AN and a 7/8″ x 20 male thread, with a sealing crush washer. This application would suit certain carburetor feed applications.

Dash AN male to straight thread male. This example features a -6 AN male and a 9/16″ x 24 male thread with a crush washer, suitable for fuel plumbing or other custom application.

Dash AN male to straight thread. The example here features -6 male AN to 7/8″ x 20 straight thread, with a crush washer. Suitable for certain carburetor applications.

Straight male to male dash AN union. Allow connection of two same size hose ends.

Male to male AN reducer. Allows connection of two different-size hose ends. Available in a variety of combinations.


Male AN to male AN 90-degree fitting. Same size AN at each end.

(Designed to allow plumbing through wall surfaces, such as firewall, rear bulkhead, etc.)

Straight bulkhead adapter. Same size AN male at each end. The longer section passes through a hole in a bulkhead wall. The exposed straight threads accept a nut that secures the adapter to the bulkhead. Separate hoses can then be connected to each end of the adapter while the adapter remains in a fixed position.


45-degree bulkhead adapter.

90-degree bulkhead adapter.

AN bulkhead T on run. All three male AN same size. The long section (that will be secured to the bulkhead) is on the main run.


AN bulkhead T. The long section is the T, which mounts to the bulkhead. All three ends feature the same AN size.


Bulkhead nut. This allows you to secure the bulkhead adapter to a wall. Drill an appropriate-size hole in the wall, pass the long end of the bulkhead adapter through the hole, and secure the adapter with this nut.
Always order the bulkhead nut based on the size of the bulkhead adapter
(-3, -4, -6, -8, -10, -12 or -16). Always match nut and adapter material. If the adapter is aluminum, use an aluminum nut. If the adapter is steel, use a steel nut.

(these include caps and plugs for AN 37-degree, AN straight thread and NPT applications)


Dash AN cap. Features a female AN (37 degree sealing cone). Designed to cap-off a male AN fitting. Common uses include capping-off a fitting when hoses are disconnected, to prevent fluid leaks or to protect fluid passages from contaminants (during engine storage, repairs, etc.). All dash AN sizes available.


Male AN plug. This can be used to cap-off disconnected hose ends when not in use. Features a male hex head.


AN straight thread port plug with O-ring seal. For capping-off an AN straight thread port.


NPT internal plug. Features male NPT thread and a female hex drive. For capping any NPT port. Available in all NPT sizes. Remember: always apply Teflon tape or sealing compound during assembly of any NPT thread.


NPT hex head plug. NPT male threads with a male hex head.

In addition to the wide array of aluminum hose ends and adapters, steel components are also available for high pressure hydraulic and other severe duty applications where steel is preferred.


Steel -AN to NPT adapters are available most all of the same sizes and configurations as aluminum adapters.

For those who wish to have their AN adapters custom anodized in other colors, bare, un-anodized aluminum adapters are available from select manufacturers (not all makers offer un-anodized items). If you want un-anodized hose ends, you need to check with the various makers. Depending on existing stock or backorder situations, you might be able to place a custom order, or you might get lucky and be able to snatch what you need from existing stock. There are several anodizing shops in the country that do excellent work. While the “standard” colors that all anodizing shops carry usually include black, blue and red, there are other shops that offer a dozen or more colors, and yet other shops that can attempt to match the color you want.
If you purchased already-anodized hose ends and adapters, but want to change color, this can be done, but you need to be aware of a few things. If the item has already been anodized, and since anodizing is essentially an oxidation process, the surface is now etched. When the original color is stripped off (chemically), the resulting surface will be rather dull. If you like a “flat” look, you’re in business. If you want a gloss surface, you have two choices: each piece must be polished before anodizing, or you can request a clear gloss finish over the color (an option not all anodizing shops offer). From a standpoint of appearance only, be aware that one of the big variables lies with the composition of the aluminum stock. Depending on the hardness and alloy makeup, some aluminum pieces will provide a glossier finish than others. Also, the same color anodizing will appear lighter or darker when applied to different grades of aluminum. If you want all of the custom-anodized pieces to match, be sure that you obtain all of the pieces from the same manufacturer!


Here’s an un-anodized aluminum AN to NPT adapter. If you can obtain these in their “bare” form, the results from custom-color anodizing will be outstanding. Otherwise, if the part must be stripped, it may require polishing before anodizing; or a clear-coat may be applied over the anodized color by the anodizing shop.

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