OK so I purchased a bunch of parts a few weeks back for a really good price and one of the parts I got in the bundle was a Quadrajet.

The carb# is: 7042240

From what I am able to tell this was originally a 1972 Buick 455 QJ. The fuel inlet looks correct. Since this is a newer carb than my '66 425 had will this still work for my application???

 

Anyone?

 

I'm not familiar with Buick carbs, but one thing that differs between years on Olds carbs is the choke setup. You may also have a different connection for the throttle cable between Olds and Buick. I think those would be the two places where you may need to modify it. The basic shape and size should be the same so it will bolt onto your engine and I believe the air cleaner will fit. If it's for a 350 motor you may not get as much fuel at wide open throttle than with one designed for a big block due to internals on the carb. If you had a Toro intake there may be some problems with the arm where the throttle cable attaches hitting your mainfold, but with a normal intake I don't know if that would be an issue. If it's a good looking piece and you have some time I'd give it a try! John

 

Thanks John. Very helpful as usual!!!

 

OK so I took the carb to a local rebuilder. He told me the Buick carb will work fine on my engine with little modification.

When I got home I started thinking..... which doesn't happen often but I figured I'd give it a shot. I'm used to working on modern EFI engines so don't have much experience with Carburetors.

This Buick carb is apparantly rated at 800+ CFM. Can a carb have too much CFM?? I figure the engine will only pull what it can so it couldn't hurt but could it effect fuel economy or power??

 

Short answer: No, not really.

Longer answer: Yes, it can affect fuel economy, if you can't keep your foot off the floorboards. The Q-Jet can be almost endlessly tuned, with power springs, jets, primary metering rods, secondary metering rods, spring-loaded adjustable secondary air valves, etc. The later models ('77-'79, I think) even have a screw-adjustable part-throttle system. They only came in 750-cfm and 800-cfm versions, with slightly larger primary venturis on the 800 models.

Bottom line, I personally would look for an 800 over a 750 for a big block. Your in-town mileage will be fine, your highway mileage will be fine (all within the limits of the rest of the engine/gearing build, anyway), and rompy goodness is very obtainable.

 

actually Yes a carb can have too much cfm. usually a problem with mechanical secondary carbs. as Erinyes said though the Qjet is very versital but is also a vacume secondary so if set right it will only take what the engine can use. with a little time and someone who knows Qjets it should work great.