307 Carburetor Questions

[rharris]

I am looking to replace the factory 2bl and intake on my 72 factory 307. I would like to go to a 4bl with electric choke. I'm thinking a performer intake and edelbrock 500. Anybody have any input? I know the engine is on the not so good end of horsepower, but the 2bl has hard starts, especially when warm. Mostly, I like working on my truck and i'm bored. . Thanks in advance for all suggestions -except for the ones that say donate the 307 for a boat anchor - it runs smooth and is original and has low miles. It will be staying for a few years yet.

[HO455]

It sounds like your on the right track. If you have a choice of runner sizes on the intake go with the smaller ones. Better throttle response and low end torque. I would also add some small tube headers or a set of ram horn cast iron manifolds would be good. With the 307 no need to find a pair of the 2" ones everyone else is looking for. And I would avoid shorty headers. All the header issues with none of the benefits. Its the classic 1975 upgrade.

[Eddie H.]

That would probably be a good set up for your 307. I have found that when running Edlebrock carburetors, it is necessary to run a 1 inch plastic insulating spacer to prevent fuel from boiling in the bowl and causing hard start problems.

[rharris]

thank you. I was planning on using the exhaust manifolds that are on it. I would entertain switching them as well. Had headers on my 454 and they pinged like crazy. Old fella that I bought my 71 350 from said the ram horn was the quitest as far as unwanted noise and to get most performance. I am not against holley - any good setups for them?

[Eddie H.]

There's nothing wrong with a Holley either. The 600 cfm electric choke model would work fine on a 307.

[Steeveedee]

I'd personally go with a Quadrajet, properly set up. I don't like the E'brocks because the throttle plates wear out so quickly, and as has been mentioned, need an insulator block to avoid heat soak. Been there done that with both symptoms. I rebuilt the original Q-Jet on my truck a couple of years ago and had to put bushings in the throttle plate (had the bushings done). It's been rebuilt before, but finally needed the throttle plate bushings at 212k miles. Some need it sooner, but not in 20k to 30k miles like an E'brock. OMMV.

[HO455]

If you go the Qjet direction (which I am a huge fan of) try to get one from a 305 to 327 if possible. The idle passages will be sized to work better with your small displacement engine. You can get decent idle quality with one off of a 350 but it won't be as easy.

[mike16]

you ought to try to get the engine running right before throwing new parts at it.

maybe new parts may not fix whats wrong

[engineer_gregh]

I did exactly what you said to my 71 with original 307. Edelbrock performer intake but with an Edelbrock 600 carb. Ran like a champ, huge improvement over the stock set up.

[rharris]

Originally Posted by engineer_gregh

I did exactly what you said to my 71 with original 307. Edelbrock performer intake but with an Edelbrock 600 carb. Ran like a champ, huge improvement over the stock set up.

Do you recommend the 600 over the 500? I just assumed the 600 would be too much.

[HO455]

I have a 600 Eldebrock 1407 on my 305. Which is the gas economy version. The PO installed it and it starts and runs fine. But I seems it could be better set up on the secondary side. But I haven't even put as timing light to it yet, so I'm sure there are improvements to be had. Qjets are 750 (or some 800 cfm) cfm and they were used on engines as small as 230 CID. I would go for the 600 so I wouldn't have regrets later if i were to step it up. And down the road a 600 should be easier to sell if needed.