Quadrajet

[FireStruck]

Is there a way to tell what size a quadrajet carb is. I know they made different cfm\'s, there has to be a way to tell.

Thanks

Steve

[ReedZ]

not really. You\'d have to dismantle it and look at the jets, etc. for sizing. They didn\'t put any markings to my knowledge on the outer casing on what size they were.

[ChevyKiD_69]

no they dont put any markings on the outside of the case you would have to pull it apart to check it. they came from factory 700 to 750 cfm.

[mzoomora]

Some were 780 cfm and I thought I had heard that the even made some in the 800 range. I dont run one now, but have in the past and liked them a lot.

[ReedZ]

Yeah,

I thought some of them went up to around 860cfm...

I could be wrong though.

[85350DROPTOP]

Big blocks were about 850

[HARDBALL]

Look inside the primarys, the smaller Q-Jet is rated at 740cfm and there is a ridge around the top of the venturi that makes it smaller.

The larger is 800 cfm and the venturi is smooth.

They both use the same secondarys and base plates.

[MARKYMARK]

theres one on the 1968 vette 427 4-speed collecting dust in at work. its most likely the 830

[Scotty_S-15]

Seems I recall reading once that the big Q-Jets came on the big Buicks, Cads, etc.

[truckinbuzzard]

All quadrajets have a number stamped on the drivers side rear secondary. You can see it when the secondary throttle actuator is open. The only thing this will tell you is the year and the engine size the carb came off of, as well as if it was a manual or auto trans. If you look down in the primary venturi and see a solid lip it should be a 750, if you see a single bump instead of a definate ring if should be an 800. Other than taking it apart and looking at the jets, etc. like ReedZ had said that is the only way i know to tell.