Need a carb suggestion

[kman67rsss]

hey guys im at the point where i will be needing a carb shortly. the motor is a 414 BBC based off a 402, 1970 vintage. AFR 305 magnum heads, JE custom dome pistons, hyd. roller cam from howards with a 236/242 @ .050 and 612/612 lift. i was thinking either a 750 or an 850. not sure what one would be better. the calculations come out bigger then a 750, but not quite 800. any help would be great. o and i plan to spin this to 6K

[TurboLark]

I would personally use the 850. All my motors have liked a carb bigger than the calculations give.

[kman67rsss]

that was the thought path i was going down. too much fuel would be easier to compensate for then not enough, right.

[Brad]

Whats going to happen when/if you over carb your engine is a lean condition. Depending on much you over carb it, anyhow. What happens is the vaccum signal at the booster is not enough to pull the fuel needed, resulting in a lean, not rich condition. You'll end up having to richen the mixture from idle into transition. Basically, alot of headaches can be found if you go to big. At most, you'll be giving up 10-20 hp on the big end. What you will gain is easy tuneability, driveability and a fun car to drive. I'd go with no more than a 750 cfm vaccum secondary carb.

[RatMalibu]

my 489 BBC shifts at 6200rpm......I'm running a holley 3310 slightly mod'd....nothing major still has a electric choke etc.

I'd agree with Brad a 750 will do you just fine

btw those are some monsterous heads for a 402 based engine......you sure you're only spinning 6k?

[zbugger]

I actually agree with the recommended 850 carb. If you could borrow one of each, you can test for yourself. The 750 will help with streetability, but the 850 should make more power with a good tune.