[66 442]

id like to know the best products to make a olds 455 respond. right now i have a mild cam, headers, and a holly 600 carb. ijust had my quadrajet rebuilt so i think ill throw it on. my son just picked up a 70 olds with a 455, headers, and a edlebrock carb. this seems vary responsive. does anyone know the best combination?

[DoubleVision]

Compression ratio plays a role, as does spark timing, and many other varibles.
A 600 is on the small side for a 455 olds, a 750 would be better, I would think a 750 carb would wake it up some, afterwards, I`d go over the spark timing, make sure it`s advancing and the weights aren`t stuck. What shape is the tune up in? are you using spiral core spark plug wires? is the exhaust corked even so it`s running headers? what rear gear ratio? these engines had 4.125 bores and a long 4.250 stroke making it a torque beast. I think your answer is in the tune, give it a bigger carb and tune it, it should respond accordingly.

[QuenchPiston]

Just keep in mind these 455's fight tooth and nail to turn above 5500rpm in mild street build. I don't know what the breaking point is, what parts it takes, to get them to rev past 5500rpm because we stopped off at a very mild port job on iron heads. Even at our point the engine/car was a blast to drive until it dropped a valve. The machine shop who built it neglected to check the valve spring retainer to under side of rocker arm clearance. Do what ever it takes to check this clearance or you will be sleeving your block too. I believe you can take a paper clip, depending on size, and use it as a go no go gauge to check all retainers. As far as revving the snot out of them, what for, they make great torque so build upon that and you should have a fun rod.

[curtis73]

The biggest limiting factor in a stock Olds engine is the heads. They breathe very poorly. Don't go crazy with valve sizes, that will just shroud them near the cylinder walls. Porting, aftermarket heads, anything is better than even the best stock heads.

I also agree that (even with proper breathing) Olds 455s don't like to spin fast. They are an undersquare engine with lots of stroke. 5500 (from what I've heard) is absolute max on a stock rotator, so don't build the upper end for more. You're spot on with the cam (mild is good). Make power in the heads, that's Olds' weakest point from a power standpoint.