Displacement On Demand: Part 2
Displacement On Demand
Part II: Building the LT1s Top End For 400-Plus Ponies (Continued)
| Next the high performance Teflon valve seals are slid onto the valve stems using plastic boots to protect the seal from being damaged by the keeper grooves.
Then a pneumatic spring compressor does its job squeezing the valve springs while the keepers and rubber O-ring are slid into place, preventing oil from passing down the valve spring and keepers.
Now that the paint is dry, the Fel-Pro head gaskets are placed on the block. The cylinder heads are placed on top of the gaskets and then tapped with a rubber mallet to get them to settle into position.
ARP head bolts are dipped in silicone gasket maker to prevent leakage, since they will be going into the water jacket. Once installed, the head bolts are tightened in a circular pattern starting from the inside. Since these are aluminum heads the bolts must be step-torqued, rst at 45lb.-ft. then 70, again in a circular pattern.
A dab of grease is put on the tips of the pushrods and the valve springs, then the pushrods and rockers are put into place. Before the rockers are tightened, Dan checks the pushrod length to make sure everything is jiving. Lastly the poly locks are screwed into the rocker studs using a 5/8ths wrench to make a half turn on the heads, then a 3/16ths Allen wrench is used to turn the set screw for it to lock. Once the freeze plugs, knock sensor, and oil pump drive gear are all installed it is on to the intake manifold.
The intake gasket is placed atop each of the heads along with a 1/4 inch bead of silicone. Next comes the intake manifold and its 3/8ths bolts, which are tightened by hand initially, then with 35 lb.-ft. of torque. A TPIS adjustable fuel pressure regulator is screwed into the fuel rail, then the O-rings of the Accel 30-pound injectors are lubed with motor oil before being pushed into the fuel rails. The assembled fuel rails are pushed into the top of the intake manifold and the 5/16ths bolts are turned until tight, then and additional 1/8 of a turn.
The customer provided a TPIS 52mm throttle body with the patented Airfoil, which is said to flow up to 900cfm. Dan connects it to the intake and wrenches the 10mm bolts until tight as the project nears its conclusion.
The MAP sensor is connected to the intake manifold with two 5/16s bolts, and the knock sensor is installed by first placing silicone on the thread to seal the water jacket, then tightened with a 7/8ths wrench. Once the valve covers and accompanying gaskets are placed on the top of the heads with the 3/8ths bolts tightened, Val Becker’s 383 LT1 is all ready to ship out. Of course we couldn’t let it slip through our hands without seeing what it could do first.
Tune in to Part III to see what this baby does when we strap it to the dyno and put it on the wood.
This article was originally published in the April 2005 issue of GM High Tech Performance and is copyrighted by Primedia Inc., All Rights Reserved.
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