Is there a rule of thumb in determining what size a Quadrajet is?

I have one that i've had for some years. It's a 17085239. Came off a 350 1/2 ton truck, 1985..

Has all sorts of markings but I don't know what is important and what is not. Curious if it's at least 750 cfm, or larger..?



-- Joe

 

Everything I've heard is they came capable of two different flow rates, 750 and 800. The 800's were used on big blocks, 455's, etc., never on SBC's.

So, depending upon the AV travel limit of this carb, it's 750 max.

 

I was hoping you would answer, but didn't want to bug you with a PM.

I have a edelbrock/carter afb 750 on the car right now. Would rebuilding this Quadrajet bring anything to the table or are they about equal ?



-- Joe

 

Since the primaries are smaller, you'll get a little better throttle response and potentially better fuel economy with the q-jet.

The info I found says that carb came off of a 305, so you'll have to do some tuning on it, both primaries and secondaries. It would be a lot easier to do if you have wideband O2 available.

Does it have the dual capacity accelerator pump? Should be an electrical connector on top of it if it does. Not a biggie if it does, not hooking it up gives you the bigger shot. I'm guessing it doesn't.

 

When looking down into the primary bores of a Q-Jet, if there are "bulges" in the venturi walls, it is an 800cfm unit.