Fuel Swapping From 2bbl To 4bbl

Tross 1991

New Member
Jul 18, 2015
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I have a 1977 Mustang 2 with a 302 and my carburetor is needing to be replaced to fix idling and fuel issue (much more detail but in short, have tried many things and a mechanic says the next starting place is the carb) and just have one question as I have had two answers.

I have an edelbrock after market (by appearance) air intake as well as an edelbrock 2bbl, but the 4bbl I have is a Holley, I was told as the intake is after market, it should bolt on still without needing a new intake. I have never done a carburetor replacement but heard it's straightforward aside from the tuning part afterwards.

Does anyone know of the Holley would bolt on before I go removing the one on there already?
 
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I agree with Big Blue, it's possible it has an integrated, removable adapter. If it doesn't, I use one of these guys:

http://www.summitracing.com/parts/mrg-1933?seid=srese1&gclid=CJf13Y3d78YCFZKRHwodkKMJwg

This will let you put a 2-bbl on a 4-bbl intake, or the other way around too. I'm actually running this on my v6 turbo since the only available 4 barrel manifold is expensive and hard to come by, and I needed a bit more fuel. I've had no issues with it. I imagine the flow isn't nearly as optimal as a made-for-4bbl manifold, but it runs and idles well.

In my experience an out of the box Holley is going to be tuned fairly well for a stock small block. A little idle mixture adjustment with a vacuum gauge, and set the idle speed, and it should run pretty good if not close to perfect. If you have a radical cam or other major mods then it'll take a bit more work. Definitely check the float adjustment though, they often don't get that quite right out of the factory.
 
I have a 1977 Mustang 2 with a 302 and my carburetor is needing to be replaced to fix idling and fuel issue (much more detail but in short, have tried many things and a mechanic says the next starting place is the carb) and just have one question as I have had two answers.

I have an edelbrock after market (by appearance) air intake as well as an edelbrock 2bbl, but the 4bbl I have is a Holley, I was told as the intake is after market, it should bolt on still without needing a new intake. I have never done a carburetor replacement but heard it's straightforward aside from the tuning part afterwards.

Does anyone know of the Holley would bolt on before I go removing the one on there already?
Do you have pics of your current setup? I'm curious to see what you're working with so I don't give you the wrong advice on expensive parts.