whats a good carb for a 307 chevy?

[beermonkey9417]

i have currently in my elky a chevy 307 motor out of a 71 camaro. it has stock heads which im currently pulling out to get cleaned and checked, and it has an edilbrock performer intake manifold and no smog stuff. the current carb i have is a 650cfm holley i think is eather a 4010 or 4050, i forget, but it has manual secondaries. and i have new hedman headers. any suggestions?

 

[Phoenyx]

If you're gonna stick with holley, I would say 550-600cfm, and stick with vacuum secondaries.. Or if you want quadrajet, find one from a 350.

But that's just my suggestion.

 

[beermonkey9417]

well i already bought a kickdown cable and bracket for the carb, will that work with the vacume secondaries?

 

[Mudweizer]

well i already bought a kickdown cable and bracket for the carb, will that work with the vacume secondaries?

Yes it will.

 

[beermonkey9417]

sweet. well now i gotta look for a 550cfm holley carb.

 

[DRIVEN]

If you find out that the heads need work look for some good used 305 heads. Same size valves (or close) but smaller chambers, better port design and hardened seats for unleaded fuel -- plus their cheap and easy to find. IMO 307s were a pretty good engine with poor heads. I ran one with #461 heads and a Xtreme Energy cam, performer intake and Carter 625, and it ran great!

 

[85 Cutlass Brougham]

Remember that the mechanical secondary Holley carbs are very sensitive to engine displacement whereas the vacuum ones aren't. I would consider a 600cfm vacuum carb (List #1850) as the secondaries will not open all the way if the engine does not need it. You can also tailor the opening with a change in secondary springs. If this is not a race car (it's a 307 so I assume it isn't), you will be much happier with a vacuum carb than a double pumper. If you were not already set up for a Holley, I would suggest a Edelbrock AFB clone or a Quadrajet off a 305 instead. Both of those have better main metering and provide better fuel economy out of the box than a Holley. Just whatever you do, don't get a Holley vacuum 750/780 (List #3310)! The idle feed restrictions are too big and it will always be stinky rich no matter what you do on a 307. That carb was originally designed as the OEM carb for a 396, and as such is set up for an engine with higher minimum fuel requirements in order to idle.

 

[DRIVEN]

^^I agree ^^. I think for your combo I would lean toward an 600CFM 1850 with vacuum secondaries and electric choke. It should run good out of the box. I ran one on a stock 283 with Performer cam and I didn't even need to adjust idle mixture. If anything it might have been calibrated just a touch rich. It would probably be perfect for your combo. I am not a huge fan of the 4010 that you mentioned earlier. They are kind of a hybrid loosely based on the old Motorcraft 2BBL used on Fords. They were mainly marketed as a "no leak" carb to compete with the Carter/Edelbrock brands. They run OK but aren't as tuneable as other Holleys.

 

[Phoenyx]

I think a 600cfm is to big for a 307.

 

[DRIVEN]

600CFM would be fine if it was vacuum secondary. 390/450 carbs are really expensive and don't leave much room for performance growth.