Broken off air tube fitting in exhaust manifold, now what?

[COPO]

I wonder if manifolds like this which was not drilled for A.I.R. was aftermarket or factory?

Not factory for 67-74 Z28.

 

[unrestored72Z]

Not factory for 67-74 Z28.

So would a manifold from a 77Z look and function the same but not be drilled?

 

[FS87LT]

Check the Chevy USA parts book and you'll probably find ONE part number for exhaust manifolds which no specification mentioned for air pump or non-air pump engines. 305s as well as 350s, too. One rh and one lh manifold number fit the normal V-8s, just as the Hooker Blackheart "enlarged runner" manifolds do. SAME exhaust exit location, too.

As GM built ONE exh manifold for each side, the factory replacements had ALL of the holes drilled in them. Chevy Parts ALSO sold steel plugs for vehicles which did not have the air pump system from the factory! Had a recessed, square place for a ratchet (or extension) to fit it for tightening. I ordered some to see what they were. Looked neat! Not nearly as evident as the raised-square pipe plugs many bought, or the brass plugs, either.

Although I have never tracked casting numbers for the A.I.R. exh manifolds vs non-A.I.R. exh manifolds, I highly suspect the casting numbers will be the same! Reason? The non-A.I.R. manifolds were the base casting, THEN the hole drilling for the A.I.R. items happened as an additional LABOR OPERATION to the base casting. ONE casting number worked for both ultimate applications.

Thanks for posting the picture and part number of the A.I.R. manifold nozzles!

FS87LT

 

[danbrennan]

My non-A.I.R. 1978 Z28 manifolds long ago broke when I was taking them off for a head swap, so I don't have those anymore. I do still have my A.I.R. plugged 1974 manifolds; in fact, I used them on my '78 Z28 after the original manifolds broke, and before I put headers on my Z28. So I can say A.I.R. manifolds worked fine for me on the '78 engine that came without A.I.R.

My '74 came with a 2 bbl 140 Hp 350 engine, the base 350 engine that year, I think.

 

[langss]

I had the problem you are dealing with. The pipe just twisted off with the fitting. It took a lot of time, but what I did was soak the fitting with WD40, and using a "Heat Gun" no flame, I would heat the Manifold until the WD would start to smoke. You could use whatever 'Penetrating Oil' you like, that's just what I have on hand. Then I would soak it again. I did this for about a week, and eventually the remains of the tube itself just came out. I had tried an "Easy-out" and it just ate the end of the tube off. It took about two weeks of heating and soaking, finally I pounded the Easy-out in the remains, and it finally just unscrewed. Like I said it took a lot of time, but I wasn't going to buy an exhaust manifold.

 

[unrestored72Z]

I had the problem you are dealing with. The pipe just twisted off with the fitting. It took a lot of time, but what I did was soak the fitting with WD40, and using a "Heat Gun" no flame, I would heat the Manifold until the WD would start to smoke. You could use whatever 'Penetrating Oil' you like, that's just what I have on hand. Then I would soak it again. I did this for about a week, and eventually the remains of the tube itself just came out. I had tried an "Easy-out" and it just ate the end of the tube off. It took about two weeks of heating and soaking, finally I pounded the Easy-out in the remains, and it finally just unscrewed. Like I said it took a lot of time, but I wasn't going to buy an exhaust manifold.

Thanks.
I can drill out the tube, I assume.
The hard part is getting the threads out considering it doesn't have a head any more.
So you used an easy-out to twist out the old threads, correct?
Do you recall what size of EO?

 

[langss]

I can go look in my toolbox tomorrow and get back to you. And yes, it just unscrewed. the threads were nasty, but I had some really small Wire Wheels, that I put in a Die Grinder, and they cleaned up enough to get a new set of "Smog Tubes" screwed in. Do use a good Antiseize when you put it back together.

 

[unrestored72Z]

I can go look in my toolbox tomorrow and get back to you. And yes, it just unscrewed. the threads were nasty, but I had some really small Wire Wheels, that I put in a Die Grinder, and they cleaned up enough to get a new set of "Smog Tubes" screwed in. Do use a good Antiseize when you put it back together.

Thanks, I will be going with plugs, with some anti-sieze.

 

[bkmont]

Thanks.
I can drill out the tube, I assume.
The hard part is getting the threads out considering it doesn't have a head any more.
So you used an easy-out to twist out the old threads, correct?
Do you recall what size of EO?

A Left handed drill bit might do the trick. Give it a good Kroil penetrating oil soaking.

 

[mech393]

i have used kroll oil soaked it for a day and then used a air hand saw with a small blade and cut into the tube in four places, and then caved the tube into its self saving the threads.