i currently have a zz4 cam in a rebuilt 355/ 113 vette heads/ 1.5 rockers/ 750 carb/ shortys/ t-5/ 3.73 posi...with this i get about 280 rwhp...would it be worth it to swap in a LT4 hot cam? or the comp 268? i don't want to do any spring change if possible...

 

The LT4 HOT cam will boost it some. Hard to say how much, without knowing the rest of the combo (compression and so on).

Whether you'd have to change valve springs, depends on what's on their now, and how they're set up.

The 268 is not a roller... it'd be better to stick with a roller.

Since this is a carb car, the LT4 cam is not ideal. It's set up for EFI to be willing to tolerate it. A carb needs no such compromise.

This cam right here should slide in where the ZZ4 one is now, with a minimum of other effort.

http://store.summitracing.com/partde...8&autoview=sku

 

Based on your info your motor is very simular to the ZZ4 crate motor and seems to be making the rated gross hp ( about 350hp). If you just add the Lt4 Hot cam you will get 15 more HP (385hp) If you wre to switch to a performer rpm manifold and 750cfm carb and 1.6 rockers you would be at 400BHP. If you were to then home port your ZZ4/L98 cylinder heads you would pick up another 30hp.
The Lt4 hot cam needs a better than stock spring especially with the recomended 1.6 rocker arms for maximum performance.

 

thanks for that f-bird88....i guessed i'd need a spring swap. it's a lot of work, but HP isn't cheap.......i also got CompCams to recommend their XR276HR-10...which needs their 986-16 springs...