PROJECT LS2, PART 3 (B)

PISTON/ROD INSTALLATION

With the cylinder bores wiped clean with a lint-free towel, apply a light coat of engine oil to the walls. After making sure that the connecting rod and cap saddles are clean and dry, install the rod bearings to the rod and cap and coat the exposed bearing surfaces with oil (I used Royal Purple Max Tuff assembly lube on our MAHLE Clevite CB-663HNK Tri Armor rod bearings) . It’s super-slippery and clings without running off, even after long periods of storage. Using a clean oil can, pump engine oil over the ring and skirt areas of the piston. Double-check all ring end gaps to make sure that they’re in the proper positions. The critical thing to remember is to avoid allowing any of the ring gaps to align with each other.

After installing the rod bearings in the rods and caps, and coating the bearings with Royal Purple Max Tuff, the ring packages and piston skirts were treated to a liberal douse of 30W oil. Instead of using a “barrel” type ring compressor, I used Summit Racing’s tapered aluminum ring compressor. This one features a split in the barrel wall and a captive worm drive clamp, which makes it adjustable from 4.000″ to 4.090″. I adjusted it to 4.005″ to match our bores.

I slid the rod and piston through the compressor (inserting the piston from the bottom of the compressor). With a bit of skirt exposed below the compressor, I inserted the assembly into the bore, using the skirts to square the piston in the bore. Using a closed fist, a smooth push against the piston dome slid the assembly into the bore easily and smoothly, with no hang-up interruptions. This is a nice ring compressor and, since it’s adjustable, it’s more versatile than a dedicated one-size billet piece.

The Lunati 7/16″ rod bolts (made by ARP for Lunati) call for a stretch of 0.0050-0.0054″, or a torque value (with oil) at 80-85 lbs./ft. I opted for the stretch method, using the Gearhead Tools billet-bodied stretch gauge. After initially tightening the rod bolts to a mere 10 lbs./ft. (enough to locate the rod cap but not enough to begin stretching the bolts), I placed the stretch gauge onto a bolt using the gauge’s pointed anvils to nestle into the dimples at each end of the bolt. I then zeroed the gauge. I next began to tighten, using a torque wrench, up to 70 lbs./ft., at which point I measured about a 0.003-0.0035″ stretch (each bolt varied, but that’s an average). I continued to tighten bit by bit, rechecking as I went, until I reached a bolt stretch within the 0.005-0.0054″ specified stretch.

It’s time consuming, but what I like is the fact that you’re actually measuring (and recording) exactly how far each bolt stretches, instead of only using torque (in which case some bolts might stretch by as little as 0.004″ or, in an even worse case, the bolt might stretch beyond the spec). Tightening by monitoring stretch is definitely a more accurate method of both achieving proper clamping load and knowing how far the bolt has stretched, instead of guessing.

Once the rods were fully installed, I checked rod sideplay. In each rod pin location, I noted 0.011″ sideplay. This consistency is yet another illustration of the precision with which Lunati makes its connecting rods and cranks. I saw no deviation at all from pin to pin.

OUR CYLINDER HEADS

For this build, we chose a pair of fully-assembled Trick Flow aluminum GenX street/strip heads, which are fully CNC-ported for optimum airflow. The clever boys at Trick Flow spent quite a few hours developing these heads to maximize horsepower and torque for the LS engine, both in computer mapping and dyno cell testing.

During the development stage of the Trick Flow GenX street/strip CNC-ported cylinder heads, Trick Flow engineers determined that the valve angles needed to change from the stock 15 degrees to 13.6 degrees in order to decrease valve shrouding, increase mid-lift airflow and to improve rocker arm-to-valve-cover clearance. Testing also proved that relocating the spark plugs in the combustion chambers further enhanced mid-lift airflow and increased rigidity of the casting for extreme horsepower applications. Additional material was also added to the rocker arm mounting points for high-rpm valvetrain stability.

These fully CNC-ported performance cylinder heads feature 215cc (LS1), 225cc (LS2) or 235cc (LSX) intake runners, 80cc exhaust runners, 64cc (LS1), 65cc (LS2) or 70cc (LSX) combustion chambers, 2.040″ (LS1), 2.055″ (LS2) or 2.080″ (LSX) intake valves, 1.575″ (LS1/LS2) or 1.600″ (LSX) exhaust valves, bronze valve guides and ductile iron intake and exhaust valve seat inserts. Assembled heads include 1.300″ dual valve springs (for hydraulic roller camshafts up to 0.600″ of valve lift), Viton fluoroelastomer canister-style valve seals, 7 degree machined steel valve locks and 7 degree titanium retainers.

Note: While the official recommended valve lift limit is listed at 0.600″, Trick Flow engineers tell us that our 0.624″ valve lift cam will be fine, providing that we check valve to piston clearance during our build, which we would naturally do as a matter of course. The recommended limit of 0.600″ is a “safe” figure for novice engine builders who might not think to check their clearances.

INSTALL LIFTERS BEFORE THE HEAD GASKETS!

BE AWARE that the roller lifters and lifter buckets MUST be installed before installing the head gaskets, since sections of the gaskets are located above the lifter buckets.

We used Crane’s hydraulic roller lifters (P/N 144536-16). These roller lifters are specially designed for use in Gen III engines. They incorporate a specially designed body with relocated oil passages that allow the lifter to retain full oil delivery even with extreme lift cams. According to Crane, this model lifter will handle lobe lifts up to 0.412″ (0.700″ valve lift with 1.7 ratio rockers), even on reduced base circle cams.

I first soaked the lifters in 30W engine oil for about 20 minutes. The lifters were then installed to the plastic lifter buckets. Simply orient the flats of each lifter body to the flats of the plastic bucket, and snap the lifter into the bucket. With four lifters attached to the plastic bucket, you can then ease the four-lifter bucket assembly into place, easing the lifters as a group into their respective bores. The lifter bucket is then secured to the block with a single 6mm bolt, which I tightened to 125 lbs./in. (I first placed a drop of medium-strength Valco thread locker onto the bolt threads). Once the lifter bucket is secured, you can then use a pushrod to gently push each lifter down for cam lobe contact. The lifters remain engaged in the buckets for proper lifter orientation (preventing lifter rotation).

In our particular application, Crane’s roller lifters are a tad longer (to allow for higher lift cams) and require the use of a 6mm spacer washer between the bucket and the block. The spacers were provided with the lifters. To prevent the spacers from sliding down while you’re trying to align the lifter bucket bolt hole, I dabbed a bit of Max Tuff lube onto the back of the washers, which prevented them from sliding out of place.

The clever aspect of the buckets is that this design allows you to perform a future cam change without the need to yank the intake manifold or the lifters. Simply loosen the rockers, remove the pushrods and turn the camshaft one full revolution. This will nudge the lifters back into the buckets to the point where they’ll stay “stuck” in the bucket bores and away from the cam lobes. The cam can then be changed without the need to remove the lifters and buckets.

HEAD INSTALLATION

After installing the cylinder deck dowel sleeves (two per deck), I finger-installed the ARP cylinder head studs (kit P/N 234-4317). The set includes 10 primary studs and five 8mm upper studs per side. All head bolt holes are blind and not open to water, so there’s no need for a thread sealant. I applied a light coat of ARP moly to the lower threads, just for the heck of it (to permit easy future servicing).

Note: ARP designed the head studs with 7/16″ upper threads. This is a nice touch-if you lose a nut, it’ll be easy to locate another 7/16″ nut (since this is a common size, you probably already have a few ARP 7/16″ nuts lying around the shop from old jobs). This makes life easier than trying to find an 11mm nut at midnight while you’re scrambling to get an engine back together.

The Victor MLS cylinder head gaskets (P/N 12589227) were positioned on the decks. Both head gaskets are marked “FRONT” at one end (actually, they’re marked for front orientation on both sides, which is helpful). If the gaskets you choose are not marked, it’s easy to flip them end-for-end and to create a cooling system problem. If your gaskets are not marked, just remember that the cooling passages on each gasket must be placed at the rear of the decks.

With studs and gaskets in place the heads were lowered onto the decks. Since we’re dealing with aluminum heads, hardened washers must be placed under the nuts. Installing the primary head inboard washers is made easier with the use of a pencil magnet (these locations are recessed, with no room for your fingers).

I coated all nut threads and undersides with ARP moly. All 10 primary stud nuts were then tightened, in sequence, in three steps to a final torque value of 80 lbs./ft. (I started at 25 lbs./ft., then stepped up to 55 lbs./ft., then to 80 lbs./ft.). Once all primary stud nuts were tightened, I then tightened the upper five 8mm stud nuts to 22 lbs./ft. These values are specified by ARP with the use of their moly lube. If using 30W oil instead of moly, values are slightly higher (85 lbs./ft. for the 7/16″ nuts and 28 lbs./ft. for the 8mm nuts).

Cylinder head fastener tightening sequence of the 7/16″ nuts is as follows:
1. Center upper
2. Center bottom
3. Second from front upper
4. Second from rear bottom
5. Second from rear upper
6. Second from front bottom
7. Front bottom
8. Rear bottom
9. Rear upper
10. Front upper

Once all 7/16″ nuts have been fully tightened, the top row of five 8mm stud nuts are tightened as follows:
1. Center
2. Second from rear
3. Second from front
4. Rear
5. Front

FRONT COVER

The front (timing) cover is a cast aluminum piece that features a front hub seal and a cam position sensor. The gasket is a metal-reinforced unit that requires no additional sealant.

Since the front cover is viewable, and since I can’t abide boring-looking stuff, I applied a thin coat of etching primer, followed by a coat of aluminum cast blast engine paint just to dress it up a bit and to prevent the bare aluminum from scuzzing-up down the road. The front cover is secured with eight 8mm x 1.25 x 30mm bolts (and two 6mm x 1.0 x 20mm bolts to secure the cam position sensor to the cover). I pitched the OE hex head bolts in favor of a set of tasty-looking ARP stainless 12-point fasteners (with stainless flat washers) (P/N 434-1502). All 8mm front cover bolts are to be snugged to 18 lbs./ft. in a criss-cross pattern.

Note: I’ll show front cover installation, along with the installation of the ATI Super Damper, in the next issue.

REAR OF BLOCK

Before installing the rear cover (which seals the rear cam area and features a one piece rear crank seal), an oil control plunger must be installed in the lower left of the block rear face. This plunger features a white plastic “dumbbell” shape with an O-ring at one end. Lube both ends of the plunger and insert into its oil passage hole, with the O-ring end facing the rear of the block. Insert until the face of the O-ring end is flush with the block surface.

The cast aluminum rear cover features a metal-reinforced gasket. I installed a Victor rear cover gasket, included in their gasket set (P/N CS5975). The rear cover is secured with 12 8mm x 1.25 x 20mm bolts. Instead of using the OE hex-head bolts, I installed ARP’s rear cover bolt set (P/N 434-1504), which includes 12-point stainless steel bolts (Hey, they’re ARP, and they look cool, so why not?). With the rear main seal lip lubed, the cover is positioned and the bolts were tightened to 18 lbs./ft. in a criss-cross pattern. I slipped the rear over in place, working the rear seal lip over the crank flange. I finger-installed the bolts and made sure that the rear seal was properly centered on the crank before gradually snugging the bolts, first to 60 lbs./in., then to 10 lbs./ft., followed by final clamping at 18 lbs./ft.

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