WHat size carb should I be using for a 305 CI engine? I got a TBI unit now and I want to go to CARB, but I dunno what size I should be using? 650 cfm?? maybe??

 

A 600 should be fine for a 305. Though if you plan for a 350 in the future a 650 would be better, instead of buyin 2 carbs.

there's a formula on this board to figure out how much cfm you need, try a search.

 

600 or 650 will be fine.

 

what happens if you have too much carb? like a 750cfm on a stock 305?

 

It'll load up like a MF'er driving in town or cruising at low rpms, once you open er up and get into the higher revs it'll go like a raped ape.

 

what do you mean it'll load up?

 

It'll load up with too much fuel (running really rich) and bog in the lower rpms.

 

You'll consitently foul plugs on a regular basis-when u pull them out they will be black as night, so the motor won't run as well as it could, excessive fuel consumption to name a few draw backs.
When I had the 305 that I bought the car with I slapped a 600VS on there just cause I had it, worked extremely well, very responsive, decent mileage if I remember-but I really did'nt/and still don't care MPG. I will say this, even if all I had was a bone stock, low compression 350, I would'nt put anything smaller than a 750 on it. sbc 350's and 750cfm carbs go together like PB&J. Till u hop'em up anyways.

 

Well if it's a Q-jet 750 and properly setup it will work great! Don't be fooled thinking that and out of the box aftermarket carb is jetted right for every engine. How can it be?