So in trying to I.D. some old Q-Jets I have lying around I see one is a Quadra-Jet with CA regulations and the other is a Quadra-Jet with Federal regulations. What's the difference between the two? Would it be better power wise, all things being the same, to use the Federal one, or is it such a small difference that it doesn't matter? Keep in mind the car does not need to pass emissions due to how old it is. Thanks.
The California carburetor would be calibrated (leaner) for lower emissions, not just jets and rods, but other things as well. Having said that, don't expect any Quadrajet to run right on your engine without having it gone through and recalibrated for your engine combo. If the engine will be run on E10, you'll need ethanol resistant parts in it, another reason to have it gone through.
So then the CA/ Fed has no real bearing on performance. As long as I have my carb tuned (which I am definitely going to do) to my vehicle and its modifications it'll be just fine? Okay thanks. Larry from our conversation the other day I went through some old Q-Jets I had and ended up finding a 7041540. Its in rough shape though, sent some pics to Quadrajetpower and waiting to see what they think. Thanks for all your help I appreciate it.
The 7041540 is a good carb to work with. The “5” in this carb doesn’t indicate California emissions. Larry is also correct that even a California emissions carb can be set up to deliver the power you would want. No major differences, just minor calibration points. Haven’t seen pictures yet, send to info@quadrajetpower.com
Thanks, oh I read on CARBS UNLIMITED (www.caarburetion.com) that's what it meant. I'll send the site another time. I sent you pics and a message yesterday at your website. The info@ one. I sent pics and a description of my situation. I look forward to hearing from you. They broke it down as 70= Rochester; 4= 1970-1975; 1= 1971; 5= model 5 being Quadra-Jet CA regulations ( for comparison 2= Quadra-Jet Fed regulations); 4= Buick; 0= Auto (Even for auto trans, odd for Manual) I saw it multiple places so figured it might be right. So what does the 5 and any other of my mistakes mean?
Something happened in 71, and it may have had to do with the strike or that fact is was the first 800 QJet body but Buick didnt use the standard Q-Jet naming conventions that year on the 455 carbs. I believe the California carb was a 940 that year... The 540 is a great carb, I've got two that I use and I like them a lot. Good castings, good calibration starting point and the advanatgae of an additional 50 CFM. Good luck!
"They broke it down as 70= Rochester; 4= 1970-1975; 1= 1971; 5= model 5 being Quadra-Jet CA regulations ( for comparison 2= Quadra-Jet Fed regulations); 4= Buick; 0= Auto (Even for auto trans, odd for Manual) I saw it multiple places so figured it might be right." Those are just the "basics" for numbers, but there are many exceptions to those rules. For example, for Olds Quadrajets thru at least 1979 ending with an ODD number may still be an auto transmission carb. For example, the 17059253's were used on 403 Olds engines and auto transmission in the 1979 Pontiac FB's. There were also a considerable number of Service Replacement carburetors produced, and those typically break a few rules for numbering. For example, a 17054910 is Service Replacement for 1973-74 Pontiac Super Duty 455's with the auto transmission........Cliff
