Quadrajet Identification

[3XBrownCutty]

My buddy gave me a quadrajet for my 350 we just got in the car, and I want to know what it actually is cfm wise.

I googled it and found there should be a circular stamping by the "rochester" cast. Mine doesn't have that, just a pink/red sticker.

I can't find any other codes or anything that bring up results on google.

What do I have??

 

[Minion1186]

most qjets came as 750 cfm units,on 455's it was 800 cfm http://www.carburetor.ca/ is where i found out my qjet is from a 350 from 1978.if it has a side fuel inlet then its a chevy carb,if its a center front fuel inlet then its an olds,pontiac or buick carb.hope this helps

My buddy gave me a quadrajet for my 350 we just got in the car, and I want to know what it actually is cfm wise.

I googled it and found there should be a circular stamping by the "rochester" cast. Mine doesn't have that, just a pink/red sticker.

I can't find any other codes or anything that bring up results on google.

What do I have??

 

[85 Cutlass Brougham]

They all have the same flow potential, but the factory limited them with a small stop on the secondary air valve which sets the actual max CFM. Cut the stop down, and you make the carb bigger by allowing the sec. air valve to open fully. You can also make the carb smaller by tightening the tension on the sec air valve return spring.

 

[3XBrownCutty]

Ok, mines a chevy. fuel inlet on the side...

85CB, you're ahead of me, I guess I have to do more research or just get to rebuilding mine. I have no Idea what any of the parts are. Yes, I have someone to help me since I'm a first timer :lol:

Where can I find the casting # thats what I'm after...

 

[Minion1186]

ok to find the casting number to find out specifically what year and model qjet you have,look at my beautiful painting skills in the pic below,where the arrow points should be the casting number make sure you can read each number,then type the second row into google(or to the link i gave you before) and look in chevy for the same cast number.

 

[3XBrownCutty]

perfect, exactly what I was looking for. Brings up 70-74 Caddy and 66-76 olds on the application list for the rebuild kit.

Thanks Minion!!

I'll have to play with the settings and stuff after its rebuilt like 85CB said.

 

[DRIVEN]

You probably have a big one...carb, that is :lol: . My understanding is that the Caddys were more that 750.

 

[3XBrownCutty]

yeah, its off of a 472 :lol:

Any educated guesses? 800 maybe??

 

[Minion1186]

i'm not fully situated with qjets,but from what i understand,800cfm model qjets were only available on Big 455 GM engines,mostly buick and pontiac.I dont actually think cadillac ran an 800cfm carb too many years if any.You can make your carb run richer by adding better metering rods and a metering rod hanger(this stuff applies to the secondaries and mainly at WOT).Remember though,800cfm is a lot of carb for any engine,just because its bigger doesnt always mean more performance,depending on how wild your 350 is will decide on how much cfm the engine will need,if it was up to me,i would go with 750cfm qjtets unless its a really high horepowered engine.

 

[G_Body_Enthusiast]

yeah you can change the hanger, the rods, etc for a richer or less rich fuel mixture.

keep in mind unless you plan on simply driving it wide open throttle from red light to red light you'll primarily being using the relatively small primaries 90% of the time. so whether its a 750 or a 800 doesnt matter too much IMO for a street engine so i wouldnt worry BUT just to know if its a 750 or a 800 is good info to have in the future if you want to race it.