Hi,

I am planning to do the usual upgrades on my 289: afr heads, cam, performer kit, 40 series muffler but first, I would like to change my carburetor.

Here is the thing, my 1967 is a code A but the last owner decided to switch from a 4bbl to a 2bbl (the carburetor broke and he was interested in getting a better mileage). Is there anything I need to do to switch back to a 4bbl? I am not sure to understand exactly the difference :/

What would be, according to you, the best carb? I know that I will get better components in the future but my engine is stock for now. I want something that will improve performances and that will still be consistent when I upgrade the rest.

(not the subject here but I am switching from C3 to T5 in 15 days and am really excited )

Thanks a lot!

 

welcome to the world of carburators.
from what I can see the only things you need to change bfrom 2bbl to 4bbl is the carb itslef and a 4bbl intake manifold.
rest should be the same.
I'd say every 5th post is about which carb would be best, so I'll leave that to the others and more knowledgable.
You just want to make sure that the carb will match to what you're planning to upgrade. which effectively means it will run bad until you upgrade.
So from this I'd get all parts at the same time and do it all at once instad of being disapponted over a new carb that is too big for your current application

 

well if your looking to go back to 4bbl, i would say no higher then 600cfm. even a 570 is good for a 289. switching carbs is pretty simple, just 4 bolts and a couple little linkages, then put the new one on and re attach everything. they still have electric and manual choke carbs so you can get either one you want. a 4 bbl carb only runs off 2 jets when driving normally, but when you really dump on the throttle then the other 2 will open. so its not as bad on mileage as some may think.

 

Yeah, the carb you need now is going to be different than the carb you need later. You could put something like a 570cfm or a 600, 625cfm carb etc on it, and tune it to make it work, but the performance won't be stellar until it has enough engine to function properly. Ultimately carb size is based on a series of things, engine size, maximum rpm, volumetric efficiency(determined by engine parts used) etc. Then when you factor in gearing and vehicle weight, you can figure what size would work best.

 

just for comparison sake, what's the cfm for the stock 2 barrel carb?

 

i have a slightly moddified 302 from 68, (intake, mild cam, etc.) and i have a holley 600 cfm... 4bbl and it runs great with that..

 

It depends on the 2bbl, but they used a different rating system. When you correct it to the same rating system as a 4bbl, 2bbls flow even less cfm than they're listed.

 

Ok, thanks for your replies. I think that I am going to wait and do everything at the same time!

Switching from C3 with 2.79 ratio to a T5 with 3.55 should be enough for now

 

That will make a big difference.

 

see my avatar

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