Small Block VS Big Block - A Game of Rat And Mouse

Looking to remain pump-gas friendly, we were shooting for a 10.5:1 compression ratio. Mike figured we'd need a zero deck height to achieve it, so the block was decked 0.020 inch to 9.780 inches. The result was a spot-on zero deck and a 10.51:1 CR.

These 1.7:1 aluminum roller-rocker arms from Summit Racing were another budget-friendly find. The set, complete with poly locks, came in at $210. Once the engine was hot, our lash stayed where we put it. No further attention was required.

The camshaft installed was a special-grind Comp mechanical roller cam ground on a 0.900 base circle. The smaller base circle provides the needed additional clearance between the connecting rods and the camshaft lobes during engine operation.

The connecting rods of choice were Scat 6.00-inch 4340 forged I-beam items with 71/416-inch ARP capscrews. Jose Diaz of Larry's Performance added Ross forged pistons with a 1.063-inch compression height to yield an approximate 10.6:1 compression with the 70cc chamber.

During the engine assembly, Diaz checked the piston-to-wall clearance to ensure that we had the needed 0.004-inch spec.

Camshaft Specs
Manufacturer: Comp Cams
Part Number: Custom grind
Type: Solid roller
Valve lift: 0.686/0.666 inch, intake/exhaust
Duration at 0.050: 268/273 degrees, intake/exhaust
Lash (hot): 0.016/0.018 inch, intake/exhaust
Lobe separation: 109 degrees

The block was decked to provide a 0.019-inch deck height, which helped us yield just under 11:1 compression at 10.7:1. In retrospect, we probably could have gotten by without experiencing engine detonation with a 0.00-inch deck to yield 11.16:1 compression. The benefit would have been a slight increase in power. These Ross pistons feature -6.00cc valve reliefs.

To fasten the Edelbrock cylinder heads down, we used a set of High Performance- series ARP head bolts with hardened washers, torqued to 75 ft-lb. These bolts are rated at 170,000 psi and are much stronger than the stock hardware.

All 400 blocks feature Siamese bores with steam holes (located on the deck) to prevent cooling-system steam pockets and to enhance coolant circulation. Consequently, small-block cylinder heads that will be installed to a 400 block require drilling three accompanying steam holes in each head. We used a stock 400 head gasket as a template and drilled 0.125-inch holes in the exact locations. The Edelbrock cylinder head instructions also describe how to perform this task.