Hi all, that's my first post but did read and learned a lot from all of you, thanks.

I'm working on my friend's 71 442 (auto) and found out that is carb was not original and would like
details about it because I can't find spec. The actual carb# is 17080242 and I think it's from a 1980 Buick or something and
I could have one that is more matching number : 7042251. But I was curious about comparing jet anf rod size.

Any spec please ?

Thanks a lot
Patrick

 

Take a look at this page it lists qjet specs Quadrajet Rods and jets suggestions.

 

Welcome. The original carb would have been Qjet number 7041257. Your 7042251 is from a 1972 455 (not from a 442, hoever).

The original carb used 0.069" primary jets, 49B primary metering rods, and AT secondary metering rods
The 7042251 carb uses 0.069" primary jets, slightly leaner 50B primary metering rods, and CH secondary metering rods that are slightly richer at W.O.T. The richer secondaries likely make up for the leaner primaries.

17080242 is from a 1980 Buick Turbo V6 in a Riviera and likely isn't even close in jetting or calibrations.

 

Joe, you should start a radio or stream a show like those car guys and call it "Ask Joe".... you'd probably get a lot of traffic....you're liken to a living encyclopedia of a lot of stuff.....appreciate and respect your knowledge, attention that you give to everyone here.

 

Wow thanks a lot Joe, that's what I needed. Forgot to say that the head on the engine is the "J" one. (too bad), do you think if i get the 7042251 I could run it as is or just change the the rods to be like the 7041257, or any suggestion of rod and jet to run with these head ?
And for the carb number (7041257), I saw on the web that if the last caracter is an odd number it's for a manual trans and even is for auto trans, do you agree ?

Thanks for your time Joe !

 

I totally agree with you !

 

Don't feel bad about posting in the "wrong" forum. People will find the post.
Welcome to Classic Oldsmobile 👍

 

The correct carb is jetted for the original engine. Since your J-head engine obviously isn't original, I'd start with the '251 as-is. Qjets are amazingly forgiving as far as jetting. The carb won't be optimized, but it will run. An A/F meter will go a long way towards dialing in the jetting for this particular engine.

 

Great !! thank you

 

Thanks Joe, that will help a lot.