[Stan Weiss]

Originally Posted by SD455DJ

Dmac, My brother Dan and I rebuilt a 1970 360 hp YH code 455 (std. in the Bonneville's) using the 100% stock #15 small valve heads (combustion chambers measured 89 cc's after a minimal cut to true them up) at 9.9 to 1 static compression. The block had been previously been bored .040 over with new cast pistons, so we had it honed to provide .0025" - .0030" clearance (we know, not ideal) for the new moly rings. The cast rods were replaced with Eagle H-beams and the factory crank cut .010/.010 with new bearings. The #15 heads had new Ferrea 1-pc stainless steel valves (1.96/1.66) with new CC valve springs and a Summit 2802 cam & lifter kit (224/234/112 @ .466"/.488") installed straight up (4 degree built in advance IIRC). We had the stock pressed in rocker studs pinned too rather than going to the screw in studs (cheap move on our part...and, again, not ideal). Again, the ports on the #15 heads were untouched and are known to flow 190/195 cfm on the intake side and 145/150 cfm on the exhaust both at .450"+ lift. With the factory cast iron intake, Q-jet, and exhaust log manifolds it made 390 hp at 4600 rpm and 512 lb-ft torque at 3400 rpm. With RA manifolds or headers, it would have easily been in the 420 hp/540 lb-ft range.

I'm not sure you could get 450 hp with stock #15 heads and lower compression, but maybe with a roller cam and headers with at least 9.5 compression.

Dennis

Checkout this 455 build with a Summit 2802. It has a dyno sheet posted. As a test see how close your simulation comes to the dyno sheet.

Stan