My brother have restored his GS455 engine, and we are about to start it up. Its bored .030 (462), crank grinded, new original pistons, arp bolted rods. Heads are 400 items, with bigger exhaust valves (43mm) and ported exhaust ports. Cam is unknown hydraulic Crane item with over .050 lift, around 290 deg. duration. Std intake, big headers. Carburettor is a Holley 650cfm double pumper (to small) ??? We installed a high volume pump kit. And primed the pump, pressure about 4.5bars with the driller. How much power should this engine give? Any suggestions for more power? thanks in advance David J
David, We would have to know more about the motor to even venture a guess. You need to know the compression ratio, and the exact specs on the cam. And yes that carburetor is way too small. you want at least a 750 or 800 CFM carb on your Buick. And watch that high volume oil pump. That is a no-no according to current practice. The bigger pump puts alot of strain on the cam gear, timing chain, and front cam bearing. You are better off with a stock oil pump and the correct clearances.
The problem is that I dont have info on the cam, its a used item from a stage 1 engine, dont know if its the original stage 1 cam or a aftermarket?!? I know that it is a crane cam, With a little more lift than .050 I havent messured the CR, but its -69 400 heads, on 462 bottom end. With std pistons. I dont know why previous owner has installed that 650 carb. What is the std carb for this engine? //David J
How can you have a 462 with standard pistons? Do you mean original pistons that are +.030? I would also get rid of that HV oil pump if you didn't check your clearances, that could easily ruin an engine fast. Plus, you mentioned large tube headers? I believe they are good for more top-end, but if you wanted more bottom-end power I would've went with the small tube. The standard carb you'd want is a 800 cfm. With what you've mentioned about the specs of the engine and if it's tuned in right, I'd take a stab of 400 hp.
A stock 70 stage 1,455 with a 750 cfm carb and cast iron exhaust manifolds yielded 376 hp. If you added the additional gain of good headers overs the stock manifolds, it makes sense that 400 hp as Rob says is a good approximation.
