Q-Jet bolt/stud specs for 71 base engine

[Chad E.]

So i just got a replacement Rochester Q-Jet for my 71 350ci/270hp with the correct date code.

But its just the carb. No gasket, bolts, or studs. I think I have found the correct gasket at a local autoparts store, but no one carries the specific part number bolts (the ones that mount the carb to the intake manifold). So I was going to just get some other bolts to use, but I need to know the specs (i.e. thread, length, diameter, etc) to get the correct ones. Does anyone know the specs on the 4 mounting bolts/studs for the Q-Jet (p/n 7041213)?

Also this will be my frst carb install, and I was going to look through the Restorer archive to see if there are any articles on installing one, but does anyone have a procedure or advice?

Thanks for all the help!!
Chad

[Edward J.]

Re: Q-Jet bolt/stud specs for 71 base engine

Chad, There was a big thread recently reguarding the bolts, lengths, and marking. I know the bolts were 5/16 - 20 threads per inch. maybe home depot or lowes may have the longer bolts. You should be able to just take a tape measure and measure from the top of carb to the base and add about 3/4 inch, To thread into the intake w/gasket.

[Chad E.]

Re: Q-Jet bolt/stud specs for 71 base engine

Thanks, Edward!

I looked for a thread but couldn't find it. I'll try searching again.

[Jack H.]

Re: Q-Jet bolt/stud specs for 71 base engine

You can usually find correct/original bolts/studs either at a scrap yard (QJets were used for a LONG time) or via one of the conventional catalog houses.

It's IMPORTANT to use the correct intake to carb mounting gasket to prevent warping the QJet throttle plate via thermal strain. You'll find several gaskets with the proper geometry, but you want the THICK version of the gasket that has thermal insulating properties.

Visually, you should spot it easily because there will be four built-in rubber insulating grommets embedded in the gasket surrounding the mounting bolt holes...

Last, follow the AIM or shop manual instructions for torquing the mounting nuts. You don't want 'er too tight or too loose. The gasket should absorb expansion/compression due to heating/cooling of the carb/intake.

[Don L.]

Re: Q-Jet bolt/stud specs for 71 base engine

I certainly don't want to hijack this thread, but regarding the snorkel can to carb gasket, I've seen them in black and I've seen them in brown color. As I recall, the brown ones I've seen are may be a little bit thicker than the black ones.

Does anyone know which (brown or black) is right, or if it even matters? I can pick up a black one anywhere. I had a brown one but mis-placed it. Before I start turning stones, I'm hoping to find out if it's even necessary.

Chad, I hope this post is of value to you and your project. Also, I believe I have a photo at home of the correct bolts for the '72 SB carb. I will have part numbers from my AIM, which you can compare to your '71 AIM to make sure '71 bolts are the same as '72 bolts. Let me know if this would help you.

[Jack H.]

Re: Q-Jet bolt/stud specs for 71 base engine

I think we're mixing apples and oranges here...

The issue I was talking about was the gasket between the intake and the carb (thick/insulated). It sounds like you're talking about the gasket between the carb and air cleaner...

[Edward J.]

Re: Q-Jet bolt/stud specs for 71 base engine

I certainly don't want to hijack this thread, but regarding the snorkel to carb gasket, I've seen them in black and I've seen them in brown color. As I recall, the brown ones I've seen are may be a little bit thicker than the black ones.

Does anyone know which (brown or black) is right, or if it even matters? I can pick up a black one anywhere. I had a brown one but mis-placed it. Before I start turning stones, I'm hoping to find out if it's even necessary.

Chad, I hope this post is of value to you and your project. Also, I believe I have a photo at home of the correct bolts for the '72 SB carb. I will have part numbers from my AIM, which you can compare to your '71 AIM to make sure '71 bolts are the same as '72 bolts. Let me know if this would help you.

Don, The thick (Tan) brown gasket for air horn is correct.

[Don L.]

Re: Q-Jet bolt/stud specs for 71 base engine

I think we're mixing apples and oranges here...

The issue I was talking about was the gasket between the intake and the carb (thick/insulated). It sounds like you're talking about the gasket between the carb and air cleaner...

It DEFINITELY is what I was thinking about in my post. That's why I started by saying that I didn't want to hijack the thread AND why I said "snorkel (can) to carb gasket".

Hope this clears things up.

Ed; I too think brown is correct. Any ideas for a source? (I just know as soon as I go buy one, I'll find the one that was on mine until recently.)

[Edward J.]

Re: Q-Jet bolt/stud specs for 71 base engine

It DEFINITELY is what I was thinking about in my post. That's why I started by saying that I didn't want to hijack the thread AND why I said "snorkel (can) to carb gasket".

Hope this clears things up.

Ed; I too think brown is correct. Any ideas for a source? (I just know as soon as I go buy one, I'll find the one that was on mine until recently.)

Don, Im not sure that anyone makes one thats correct, they are about 3/16 thick. they ones I have seen are not as thick and color are just a bit off.

[D S.]

Re: Q-Jet bolt/stud specs for 71 base engine

So i just got a replacement Rochester Q-Jet for my 71 350ci/270hp with the correct date code.

But its just the carb. No gasket, bolts, or studs. I think I have found the correct gasket at a local autoparts store, but no one carries the specific part number bolts (the ones that mount the carb to the intake manifold). So I was going to just get some other bolts to use, but I need to know the specs (i.e. thread, length, diameter, etc) to get the correct ones. Does anyone know the specs on the 4 mounting bolts/studs for the Q-Jet (p/n 7041213)?

Also this will be my frst carb install, and I was going to look through the Restorer archive to see if there are any articles on installing one, but does anyone have a procedure or advice?

Thanks for all the help!!
Chad

Chad, I started a thread titled 1970 Corvette Q-Jet Bolts that should answer your
questions. It became extensive complete with photos and was quite informative by responders. It evolved to the studs on the rear of the carburetor.

Scott Sims
Texas Chapter