750 cfm or 800 cfm carb for 1967 GS 400??????

[joshhirst13]

Hey guys. I'm wondering If putting an 800 cfm Rochester Q jet on my 400 Engine is a good idea or bad idea. I eventually want to get a 455 in the car, but was wondering if
1. Would the 800 cfm even create any more power versus the 750 cfm
2. Being that I eventually want to use a 455 would having the 800 be worthwhile
3. I've heard that you can install an electronic choke to help with cold starts. ( are these worth using, easy to install, & if do what's the best one to use & where can u get it)
Thanks,
Josh

[carmantx]

Hi Josh, hopefully I can help you out here.
I say, go to the 800cfm Quadrajet. The 455 will especially like the extra cfm that it will provide.
You can get a 75 or 76 Buick Quadrajet that had the hot air choke, and convert those to an electric choke if you need help starting on a cold day. I build these all of the time.

My main advice is to make sure you get a true original Buick big block Quadrajet and either build yourself or have a good reputable builder do it for you. Don't get one from a big remanufacturer.

[joshhirst13]

Thanks a ton. Would this be a good carb:
1973 Buick GS 455 Stage 1 Rochester 800 CFM Carburetor 7043240 LA. Originaldate code 2742
Thanks,
Josh

[carmantx]

That is an 800 cfm Buick 455 carb. Not a stage 1 carb. I use these 7043240 carbs all of the time. You want one in original condition with original upper section and base plates.
pthis is a divorced style choke though and would not work for electric choke conversion.

[joshhirst13]

Thanks for the info. If I decided to go without an electric choke would the above 1973 carb work on a 1967 Buick GS 400 with an automatic transmission? If I wanted a 1975 or 1976 800 cfm carb what serial #'s would I be looking for?
Thanks,
Josh

[carmantx]

yes, that carb is a great Buick 800 cfm carb and was for an automatic trans.

If you want to go to an electric choke, look for a 7045240, or a 17056240

[joshhirst13]

Will do!!! I've gotta get rid of that boat carb. Unbelievable. I can't believe someone would do that?
Thanks again,
Josh

[joshhirst13]

One more thing. Can I use the electronic choke carbs as an old style choke until I decide to upgrade to electronic or is that not doable?

[joshhirst13]

Well now that I've figured out that my carburetor is a marine/boat carb I'm on a quest for a new carburetor & since I'm going to spend the money on a new carb I might as well go for the best. Anybody know of someone selling a Rochester Stage 1 carburetor? I'm sure it's a long shot but why not go big?
-7040246
-7041242
-7042242
-7043242
Thanks,
Josh

[BGS400]

Josh,

I have a carb from a 1971 GS 455 (7042240 MB) date code is 1971. It needs to be rebuilt. Let me know if you are interested.