Top Class 565: Trick Flow Builds a Chevy 565 Short Block Assembly

Roller cam bearings, like these from Dart, are a plus in a race engine for a couple of reasons. They can handle very high valve spring pressures better than plain bearings, and they help reduce power-robbing friction--every little bit counts in high horsepower, high rpm engines. They do require a specialized installation tool.

Main bearing clearance is checked by bolting the caps to 100 foot-pounds with the bearings installed, then measuring with a dial bore gauge. Recommended clearance with coated bearings like these Clevite H-Series bearings is .0025-.0032 inches.

The pistons are from JE. Designed for open combustion chamber cylinder heads, the forged pistons have a 46cc popup with two valve reliefs. Vertical gas port holes drilled from the deck of the piston into the top ring groove and behind the ring. The holes direct cylinder pressure behind the compression ring and seal it against the cylinder wall. This helps prevent ring flutter and extends the power curve upward in the rpm range.

Todd torques a cap on one of the Manley H-beam connecting rods to 95 foot-pounds. He will then use a bore gauge to measure bearing clearance. The Manley rods are forged from 4340 steel alloy that has a compact, uniform grain structure for ultimate strength. The wrist pin and big end bores are honed to a +/-.0002-inch tolerance, and the wrist pins have bronze alloy bushings.

The bearing tolerances for a big block Chevy are .002-.0032 inches. Todd checked clearances on all eight rods; each speced out to .003 inches. The Clevite H-Series bearings are .001-inch oversized to insure proper clearances.

The JE pistons come with wristpins and double Spiro locks. Todd gently uncoils the locks before installing them so they go in easier.

The JE piston rings are a file-fit type. The top ring gap is .018 inches; the secondary ring gap is .020 inches.

The JE piston ring set features a .043-inch ductile iron top ring with a plasma-moly coating. The ring is barrel-faced to maintain just enough contact with the cylinder wall to seal properly with the least amount of drag. The cast iron secondary ring has a reverse torsional taper face allows the ring to twist in the land, forcing the edge into the cylinder to better catch oil that gets by the oil ring. The oil ring itself is a low-tension 3mm ring with a chrome-plated face.

The Dart Big M block takes a standard two-piece rear main seal. Todd likes to use a light coating of silicone on the seal surfaces of the block and the rear main cap to help prevent oil leaks.

With clearances checked, bearings lubricated, and piston/rod sets assembled, it’s time for assembly. First up is the Callies Magnum crankshaft; forged from 4340 steel, the 4.250-inch stroke crank has gundrilled mains and fully profiled counterweights. Those counterweights are strategically placed to reduce imbalance forces over the entire length of the crank to improve bearing life and reduce wear.

The main caps are torqued to 100 foot-pounds in three steps: 50 foot-pounds, 70 foot-pounds, and a 100 foot-pounds.

Todd checks crank thrust (endplay) with a dial indicator. Acceptable endplay for a big block Chevy is .003 to .010 inches; ours came in at .006 inches.

With the cylinder bores lubed with ATF fluid, Todd pushes the piston/rod assemblies into their new homes. Notice he doesn’t use a mallet or other tool to get the piston in. That’s because he’s using an ARP tapered piston ring compressor, which gradually compresses the rings as the pistons is pushed into the bore. That allows the piston to enter the bore smoothly--no mallet required.

The rod caps are torqued to 95 foot-pounds in increments of 50, 70, and 95 foot-pounds.

The COMP Cams mechanical roller cam is slid into place. Duration is 283 degrees/296 degrees @ .050; lift is .824/.785 inches. Lobe separation is 144 degrees, and the intake centerline is 110 degrees. The cam is ground for a 1-8-7-3-6-5-4-2 firing order (swaps cylinders four and seven) for extra high-rpm horsepower and reduced crankshaft harmonics.

Accurate cam timing is critical on any race engine, but doubly so on a large cubic inch, high-rpm big block. Unlike timing chains and gear drives, a Jesel belt drive does not transfer the crankshaft (torsional) harmonics to the cam that can cause cam timing to jump around. Here, Todd checks camshaft endplay with a dial indicator.

The Jesel belt drive is a “dry” system that requires no oil lubrication. It also allows up to eight degrees of cam adjustability (either advance or retard). Jesel recommends replacing the belt annually.

One 565 cubic inch short block, awaiting the super-secret Trick Flow cylinder heads, valvetrain, and an oiling system. We’ll show you all that and more in the next installment.