Cadillac Carburetor on K20 Suburban?

[chewiebarker]

Can anyone help me figure out/confirm whether the Quadrajet carburetor on my 1971 K20 Suburban (manual) is the original carb or not? Also whether this carb, if not original, is a cause of bad performance on a Suburban vs. its intended purpose?

In the pic you can see that the number is either 7042237 or 7043237. The number is then followed by 1662.

I tried to look up these numbers online and can only find something on the first 7042237. According to several sources, including Cliff's High Performance, the:
70 = Rochester
4 = 1970-1975 era
2 = 1972
4 = Quadrajet 4BBL Federal Standards
3 = CADILLAC
7 = Manual

Obviously, if there are no exceptions, this is not the correct carb. But I was wondering if these are strict standards or whether, for instance, a Sub like mine built in JULY of 1971 might end up with a 1972 year carb. Or whether GM interchangeably, or consistently, used carbs for subs from caddy's. I already confirmed that my block is a Vette block, so...I don't know.

Finally, should I rebuild this and use it, or look for something specifically designed for my Suburban? I don't care so much about 'matching', I don't think my truck will ever be a showcar, but I do care as to whether it is performing properly. It definitely needs a rebuild for proper operation, I just don't know whether a caddy carb is supposed to work with this truck.

Thanks for any insights. I appreciate all I learn on this board from all of you!

[chewiebarker]

Also, upon further reading of Cliff's page, the 1662 following the carb id indicates that the carb was produced on the 166th day of 1972. So I suppose that guarantees it is not original to my Sub...

Still, should I run it?

[chewiebarker]

Chicago Carburetor has a rebuild kit for this specific carb. See pic. It states it is for a 7.7L 472 or 8.2L 500 Caddy engine. Should I use this rebuild kit give that I have a 5.7L 350? I wouldn't think this carb would be appropriate give the difference in size and fuel requirements? Help!

[LockDoc]

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The different carb applications are listed in the back of the "Chassis Service Manual" for your truck. That would probably be the easiest way to tell what the carb number should be. That's the way I found the correct carb for my '68 CST with a 327/TH400.

I would think that carb would be too big for your engine....

LockDoc

[chewiebarker]

Thanks Doc! That must be why I smell excess gas when I drive it. Looks like I am going shopping! It has always felt boggy too. I just assumed it needed to be rebuilt.

[Keith Seymore]

Originally Posted by chewiebarker

But I was wondering if these are strict standards or whether, for instance, a Sub like mine built in JULY of 1971 might end up with a 1972 year carb. Or whether GM interchangeably, or consistently, used carbs for subs from caddy's. I already confirmed that my block is a Vette block, so...I don't know.

No, and no.

Since you have already confirmed the Vette block then you know the engine assembly is not original. A Corvette engine would not even be in a Suburban assembly plant (unless your truck was built in St Louis).

K