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This has proven to be a fairly easy build. The LS series-both Gen III and IV-shows definite promise.
by Mike Mavrigian
all photos by author
Our LS is now ready for induction and ignition.At this point, our LS2 is a complete longblock. Here, we’ll cover a number of subjects leading up to our current build status. As I’ll mention at the end of this article, we’ll cover the intake and ignition systems in the next project article installment.
REAR MAIN SEAL
The one-piece rear main seal features two sealing lips. When installed onto the crank, the rear lip must face outward and the front lip must face inboard, toward the engine front. In order to position the front lip forward, insert a nylon seal installation ring into the seal opening, installing the ring from the rear cover’s face, toward the inside of the cover, which will push the front lip forward.
Carefully position the rear cover, with installer ring in place, onto the crank flange and gently push the cover into place. The trick is to keep the cover, seal and ring square to the crank flange. Once the seal slides over the crank flange, the installer ring will fall out. This may take a few tries since the installer ring has a habit of popping off before the seal is started on the crank flange. Before fully seating the rear cover, inspect using a small penlight to make sure that the front seal lip is angled forward around the circumference of the crank flange.
If the rear seal is installed with both seal lips angled rearward, you’ll have a nasty rear seal oil leak.
WINDAGE TRAY, OIL PICKUP AND OIL PAN
The Moroso windage tray secures to the main cap studs, requiring six 10mm x 1.25 nuts and loc washers. Since the windage tray mounting holes and relief holes were likely designed to accept the OE 8mm studs, I drilled the mounting tab holes out to 0.410″ for the larger diameter ARP studs. I also opened up the relief holes in the tray itself to allow sufficient room for socket wrench access to these nuts. With the windage tray in place, the oil pump pickup was installed.
Again, I drilled out the pickup tube’s mounting bracket hole to 0.410″ in order to secure the bracket to one of the ARP studs. No big deal. The oil pickup connects at two points: the attachment to the oil pump and the pickup tube bracket toward the rear of the engine. When installing the pickup, be sure to first install the appropriate O-ring onto the pickup tube exit, where the tube engages into the pump. The mounting tab that secures the pickup tube to the oil pump requires a 6mm x 1.0 x 20mm bolt. For extra security, I applied a drop of Loctite 242 thread locker to the bolt threads.
The Moroso oil pan installs to the block using 11 8mm x 1.25 x 20mm bolts and three 6mm x 1.0 x 20mm bolts at the rear engine cover area. You can probably get away with using bolts as long as 30mm as well. A cast aluminum OE pan requires longer bolts, the length of which varies depending on the specific OE pan.
However, the Moroso pan features a pair of 90-degree -10 tubes on the left side to plumb to a remote oil filter. Between the lower tube and the pan rail, there isn’t enough clearance to insert a bolt, so in this single location you’ll need an 8mm x 1.25 stud and nut. The stud should protrude no more than 0.750″ from the block’s rail surface. Be sure to install the stud to the block’s rail before positioning the pan.
PUSHRODS
The OE LS2 pushrod length is 7.400″. Since I never assume pushrod length, I determined pushrod length using an adjustable pushrod checker. Also, Trick Flow notes that its heads are 0.100″ taller than stock, so checking was worth the time. After careful measuring on both intake and exhaust locations, the Harland Sharp roller rockers showed a nicely centered contact patch on the valve stem tips at a pushrod length of 7.500″. I then selected a set of 5/16″ one-piece forged pushrods (Trick Flow P/N TFS-21407500).
ROCKERS
Our full-roller rocker set is Harland Sharp’s SLS17. These are forged aluminum rockers with needle bearing trunions and roller tips. Each rocker pair is bridged together by a common pivot shaft. Each rocker is mounted to the rocker pedestal area on the cylinder head with an 8mm x 1.25 socket head cap screw (supplied in the kit), with a flat-head spacer that determines the installed rocker height.
Be aware that it’s very common for the threaded bolt holes in the cylinder head’s intake rocker mount locations to be tapped through and open to oil. If this is the case, apply a small dab of thread sealant to the intake rocker’s mounting bolt threads. In our build, I used a dab of Hylomar sealant paste to each intake rocker bolt.
With pushrods in place and oiled, I installed the Harland Sharp rockers while each pair of lifters were on base circles (essentially unloaded and zero lash) and tightened the mounting bolts to a value of 22 lbs./ft.
The Harland Sharp rockers we chose are 1.7:1 full rollers designed to directly replace the OE rockers. In addition to the rockers we used, Harland Sharp also offers adjustable 1.7:1 rockers for race applications (requiring shorter pushrods), as well as 1.8:1 versions.
FRONT COOLANT CROSSOVER PIPE
This one-piece tube assembly connects the left and right side upper coolant vent ports of the heads, located at the top front of the heads. This tube assembly serves to equalize coolant pressure between the heads and provides a handy bleed-off feature. This assembly attaches to the front of the heads with a pair of 6mm x 1.0 x 30mm bolts. Sealing is accomplished either with oval gaskets (supplied in our Victor engine gasket set) or with built-in O-rings. Our crossover pipe’s blocks already featured O-rings, so we didn’t need to use the individual gaskets. The T-pipe of the crossover tube can connect to the upper coolant hose to allow a coolant air bleed. The same coolant vent ports located at the rear of each head are simply blocked off using GM block-off caps.
WATER PUMP
We chose Edelbrock’s aluminum LS water pump (P/N 8896). This pump mounts to the block with six 8mm x 1.25 x 80mm bolts. ARP’s water pump bolt kit (P/N 434-3202) includes these bolts in polished stainless with 12-point heads (requires the use of a 12-point 10mm socket wrench) and a pair of 6mm x 1.0 x 20mm thermostat housing bolts. If you test-fit the pump to the block without gaskets, you’ll find that the pump’s upper left rear body hit the upper left timing cover bolt head. Not to worry, with pump gaskets in place, clearance will be fine.
Either the ARP bolt and washer or an OE bolt with built-in washer flange will clear. If you’re planning to use a different bolt, simply be aware that the total height of the bolt head and washer can’t be greater than 0.363″ before it’ll hit the pump.
In order to seal the pump to the block, I chose the stainless steel seal-printed gaskets (the Victor set thoughtfully offers both cut gaskets and the metal gaskets, providing a choice).
I tightened all six water pump mounting bolts to a value of 18 lbs./ft.
The Edelbrock water pump pulley (P/N 8898) was then installed onto the pump using four 5/16″ x 24 x 5/8″ flat-top hex-drive screws (provided with the pulley). Use a 3/16″ hex wrench.
Note: For a carb setup that uses a distributor and the GM distributor adapter (P/N 88958679, $419 at Scoggin Dickey), the stock water pump style won’t clear this distributor adapter. The only water pump source that we’re aware of for a carb/distributor setup is Wegner Automotive at (800) 652-0406, ext. 15416 (actually developed by both Wegner and EMP Stewart, and made by Stewart).
Gary at Wegner tell us that this special billet pump tags at about $350, plus you’ll need a complete pulley setup based on your specific needs. The carb/distributor deal was initiated as a result of NASCAR Camping World Series late-model rules in which teams run LS2 engines but were forced to run carbs and distributors. So, a water pump and pulleys are available, but it’ll cost ya.
Note: I feel the need to compliment MAHLE for its Victor gasket set. This set was incredibly complete, including all of the gaskets that you’d expect and more. The rear seal included a nylon installer tool already fitted to the seal, fuel injector O-rings were included, unique LS-style valve cover rubber grommets, oil pan gasket, front and rear engine cover gaskets, top valley cover gasket, exhaust gaskets, water pump gaskets, oil pump O-ring, valve stem seals, formed silicone valve cover seals, etc.
The gasket kit was very well thought-out, and was definitely LS-specific, not just some generic catch-all set. Nice job, Victor.
COOLANT AND OIL SENDERS
The oil pressure sender screws into the tall bung stand at the valley cover’s left rear. The coolant temperature sender screws into the left cylinder head, toward the front, just ahead of the No. 1 exhaust port. Remember to plug the water port on the right head (rearward of the No. 8 exhaust port).
This requires a straight-thread 12mm x 1.5 plug. Unfortunately, this plug is not available individually from GM. Apparently you need to buy a complete head in order to get this piddly little plug. My solution was to use a 12mm x 1.5 x 15mm bolt with the addition of Teflon sealant on the threads and a crush washer under the bolt head. Thanks a lot, GM.
By the way, even though this is supposed to be an all-metric engine, the coolant temperature sender hex requires the use of an 11/16″ wrench (it’s in-between 18 and 19mm).
CRANKSHAFT POSITION SENSOR
The crank position sensor (GM P/N 12560228) installs into the block’s right side, in line with the reluctor wheel. Lube the sensor’s O-ring lightly with oil and insert until seated.
The sensor’s bracket tab is then secured with an 8mm x 1.25 x 10 – 15mm bolt. This is a blind hole, and the bolt will bottom out at a depth of about 19mm.
KNOCK SENSOR
The knock sensor (required if you’re running computer management) screws into the left side of the block and is secured with a mounting tab. Instead of obtaining this from GM, I saved a couple of bucks and bought a Standard brand (P/N KS211).
INSTALLING A KEY PIN IN THE CRANK SNOUT
The LS design normally uses an interference-fit damper with no keyway register. If you want to ensure that the damper won’t slip and rotate during engine operation, ATI’s LS1 Crank Pin Drill Fixture (P/N 918993) allows you to install a 0.187″diameter dowel pin that will engage into the ATI Super Damper’s female keyway.
Slip the fixture onto the crank snout. I measured the exposed snout length from the snout tip to the face of the oil pump gear so that I could readily reference the maximum depth location for the fixture. I then removed the oil pump and marked a line on the snout at that point.
Using a small square, I then drew two lines parallel with the crank key and extended those lines to the front edge of the snout (I planned to drill the hole in line with the keyway). Remember that the oil pump gear features a single I.D. keyway. If you position your new pin too close to the block, the pin must perfectly align with the key, otherwise you won’t be able to service the oil pump in the future without knocking the pin out. There’s not a lot of available real estate on the LS crank snout, so unless you’ve precisely aligned the pin with the existing key, more than likely you’ll need to remove/reinstall this pin whenever oil pump service is called for.
With the drilling fixture slipped onto the snout, I rotated the fixture until the fixture’s drill hole was in line and centered between the keyway lines.
I installed a spare damper bolt to secure the fixture in place to prevent rotation. By the way, the reason to use an old or spare damper bolt is to prevent accidentally drilling into the bolt shank. Granted, you won’t easily drill into this bolt, but there’s no sense in nicking this high-torque bolt when you can avoid it.
I then installed the 11/64″ drill pilot and secured it from rotating with the kit’s lock-down screw. Using the 0.1690″ drill bit supplied in the kit, I then drilled a hole all the way through the snout wall into the snout’s center bore.
Next, the hole must be reamed to 3/16″, using the kit’s reamer on a low-speed drill (one in/out pass only).
After cleaning the surfaces and the crank snout bore, install the oil pump if not already in place. Next, a 0.187″ diameter dowel pin (supplied with the kit) is inserted into the hole and carefully tapped into place until 0.093″ remains exposed on the snout outer surface. Once the timing cover is installed, the damper adapter hub can be press-fit onto the crank snout while aligning the hub’s keyway with the newly installed locating pin. Installing this pin is an option for a naturally-aspirated engine, but highly recommended for a supercharged, turbo and/or nitrous setup. I installed a pin in our crank both because I thought it was a good idea and to illustrate this for the benefit of our readers.
Note: Drilling the Lunati snout took a while (it’s tough stuff). If you plan to use a cordless drill, be sure to have a few spare batteries charged up and at the ready.
Tags: ARP FASTENERS, CRANKSHAFT POSITION SENSOR, EDELBROCK, ENGINE ASSEMBLY, FASTENERS, GASKETS, HARLAND SHARP, KNOCK SENSOR, LS, LS2, MAHLE, MELLING, MOROSO, OIL PAN, OIL PICKUP, OIL PUMP, PROJECT ENGINE, PUSHRODS, REAR MAIN SEAL, ROCKERS, ROLLER ROCKERS, SCOGGIN DICKEY, SENDERS, TRICK FLOW, VICTOR, WATER PUMP, WEGNER, WINDAGE TRAY
