I've removed the most of the AIR system at this point (90 Formula, L98/T5, ESP autocross car). Just waiting for the AIR delete pulley to come in from gmpartsdirect.com (Part # 10186167).

After much scouring through searches on the board, I'm still at a loss of how to plug the holes in the manifold. I see 3 options:

1) 1/4" NPT. Not correct for the hole, but will tighten up before bottoming out. I don't know of anything I could use to seal the connection any better. Readily available at standard home stores (Lowes, Home Depot, etc). [edit] - also, given that I can get brass ones, maybe they'll conform enough to seal.

2) Crimp then braise a tubing stub and reuse the factory pieces. Seems straightforward enough, but not a very clean installation. Advantage - this will seal pretty well.

3) Correct way - 5/16" inverted flare plug. These seem to be the mecca I'm after. However, I can't find any that are either A) long enough to actually hit the bottom of the threads to seal or B) have a smaller head than base so they can be threaded in the whole way. For example - http://www.smithfast.com/ifplug.htm The heads would hit before sealing in the base of the hole.

Can anyone provide some much needed assistance? Yes, I've checked McMaster-Carr, same deal

Thanks!

 

FYRCHKN did his, but I dunno what threads he used fr sure, but I think he used the 1/4" NPT. Since the AIR tubes attached to the sides the manifolds & low, it does LOOK modified, or anything is gone.

Since I just moved to a non-emissions county & Billy Bob won't notice anything missing anyways (he didn't even LOOK under my hood last week at inspection time) I'll do my this year to!

 

How much would you want for the drivers side air tube ?

 

Mine are cut and no longer usable.

 

I'm not gonna sell them. Just because I don't get tested for emissions, it doesn't mean they aren't supposed to still be there. If I get popped for not having them, it'll be an easy fix to put them back on for inspection.

I have a pair of AIR tube fittings sitting around though. I just moved, so they might be hard to find. I know I haven't seen them yet.

 

1/4" NPT with some red locktite did it for me...

The brass ones from home depot, square end.

I just tightened with a wrench till it got to hard to turn anymore. I don't think they ever bottomed out though.

 

Good luck getting that delete pulley anytime soon. I ordered mine on March 4th and it has yet to arrive. Ill never do business with GM parts direct again!

 

Hawk's has them and shipping is fast (just installed mine).

 

Update

I went with 1/4" NPT brass plugs. Took a bit to find ones that had a smaller head than the thread (just in case). Cranked them in and they getting fairly snug just as they hit the bottom of the machined flare fitting in the manifold. Seals just fine.

Also found a baked/shredded plug wire on #8. Stopped up at the local auto parts, got a replacement 8mm for $3.18. Fired it up and it sounds much better. Who knows how long that cylinder wasn't firing. It certainly put out some black smoke when I started it. I figure it's due for an oil change anyways, and the extra gas in the cylinder just proves that.

BTW - these have similar threads - 1/2" 20tpi , 5/16" inverted flare, 1/4" NPT (just tapered). I have allenhead 1/2" 20tpi bolts if the NPT plugs don't work.

 

think i just used 1/2" steel pipe caps i got at a home improvement store. No sealing or anything, they fit well

 

Guys.......just found the correct part number for the manifold plugs. Edelman number 120500. Should be available at most GOOD auto parts stores. I'm picking mine up from Auto Zone tonight. Thanks to Randy from Eckler's!

 

That # doesn't exist on Eckler's site, nor do any manifold plugs come up searching or browsing....

 

These plugs are available at any good auto parts store with the Edelmann number 120500. I added some never seize to the threads and they went in and sealed perfectly.

 

i used 1/4" galvanized pipe plugs. i got them for like 30 cents a piece at Ace hardware.

i just used the reciprocating saw to hack off the tube, then heated up the motor a lil, then stuck a socket on them. then i put teflon tape on the plugs and tightened them down...

worked fine for me without any leaks

 

For anyone in 2020 looking for this, here's a list of keywords and a link to the summit part. Also don't get coronavirus.

https://www.summitracing.com/parts/edd-120500

AIR tubes, plug, 5/16, plugs, 1/4, A.I.R. exhaust manifold remove delete holes NPT air pump removal smog delete why is my car slow federal barely legal camaro

 

The ultimate easy button fix, if you don't need to save the air tubes, is to just cut the tubes flush with the nuts, then weld the tubes closed. No need to even remove the old tube nuts. If you do decide to put the air back together, unscrew the welded plugs, screw in a good air manifold, and away you go.

Rock Auto has the Edelmann plugs too, $0.64 each. https://www.rockauto.com/en/moreinfo...854912&jsn=255

 

Are you guys removing the air tubes with the manifold still in the car, or are you removing the manifold?

 

All you need are these.....

 

I did it with installed manifols. But my engine has just 20k miles and the car was very well maintained over the last 30 years. 7 bolts where easy to remove. I had to heat up just one of them with an open flame for a few seconds, then it opened. I recommend to bath them in a good rust remover one day before removing and heat them up with a little open flame burner.

 

If they've been there a few years they can be next to impossible to remove, and they make the manifolds more difficult to remove also, especially if you have big hands. I typically soak them down in penetrant before I start and then start with loosening what I can get to without much hassle, then I just cut them off in sections (Wizzer wheel, body saw, hack saw, Dremel cutting wheel...) till I can put a socket on them and just back them out.

WRT to the threads they're 9/16-18, which is the same thread as a 5/16" flare fitting and similar to a 1/4npt fitting. 1/4npt plugs are tapered so they will seal if you get them tight, but they will be next to impossible to get out later. I use 9/16-18 grub screws (you can get them as hardened Allen heads at most hardware stores for cheap) with a little anti-seize on them and they seat/seal off fine and are easily removable later... and cheaper than the other solutions.

 

I just used overcooked, stale, expired Lit'l Smokies from Hillshire Farms. Leave em out in the sun for a few hours until they turn into a rock hard solid, slather them in Famous Dave's BBQ sauce, and crank em in until they seal. Works as good as anything.

 

I managed to remove 4 of the 8 in flare fittings in one piece. The other four, the flare fitting actually broke in half. So, now there is a small part of the tube and a half a flair fitting sitting in the manifold. Two questions; if I drill them out do I need to worry about too much debris dropping into the manifold and making it's way through the exhaust?

Second, if I can't remove them, can I just exhaust putty them and seal them that way?

Thanks!!
David

 

I'd be concerned about the shavings going into the catalytic converter. Mine also broke off in the holes. I crammed bolts slathered in exhaust putty into the tubes. It seals like 92.48% of the problem.

 

I understand, although it sounds like eventually I'll have to replace the catalytic converter as the air not being injected into it may cause it to fail prematurely.

I have the proper 5/16" inverted flair plugs. Is there an ultra high temp thread sealant I can use on those to make sure they don't leak? Most thread sealants I see are 4-500 degrees max. Thanks!

 

I don't have a cat so it wasn't a concern for me. I'd suggest upgrading to a modern one that doesn't need air, it'll probably flow better as well.

Sealant is not used on inverted flare connections, that's an NPT thing.

 

Ahhh, okay, thank you!

 

I have 1/4" NPT plugs. Fit perfectly. Haven't started the motor yet, but can't imagine them leaking.

 

But they don't fit perfectly, because it's NOT pipe thread (which is tapered).
The CORRECT size is 1/2"-20 BOLT thread, which is what is used on a 5/16" inverted flare fitting.
How many times do I have to keep repeating it??...

 

The correct size is 5/16" inverted flare. Of this style https://www.mcmaster.com/products/in...rass-tubing-9/. ¼" NPT DOES NOT "fit perfectly", because they're a tapered thread while the threads in the manifold are straight, and the thread pitch is different. However, ¼" NPT is "close enough" to fit, especially if you use brass, since the threads will deform to fit the cast iron manifold.

TL is correct that the thread size and pitch for 5/16" inverted flare nuts is ½"-20, and that the manifolds' threads are that size, and NOT ¼" NPT. For reasons not known or comprehensible to me, it has become common, since inverted flare fittings have become FAR LESS common, to describe them by their thread pitch instead of by their tubing size. Thus, if you could get some ½"-20 set screws (Allen head) or the like, they would thread right in by hand, and if they were flat enough on the bottom, they might even seat well enough against the flare, to make a good seal on their own; especially if some sort of sealer was used that could withstand the temp, such as Teflon tape. Something kinda like this maybe. https://www.mcmaster.com/94105A730/ The seal doesn't HAVE TO be "perfect" anyway; there's not all that much pressure there to begin with, and a tiny amount of leakage can be tolerated.

Butt hay, given the fact that it's just a car, and that if something works well enough to get the job done, then it's ... good enough ..., the NPT plugs are probably adequate. Sometimes "perfect" is the enemy of "good enough" anyway.

 

I ran my car today with 4 NPT pipe plugs. The world didn't collapse. But all the liquid wrench & pipe dope was burning off, so it was hard to tell. The passenger side AIR tube is not off yet, and doesn't seem to be coming off. The drivers side took enough time...

 

Quite so. Many people have reported "adequate" success. Given that there's not much pressure there, and the consequences of a small leak there (emphasis on small) are generally tolerable, and that if you use brass plugs the mismatched threads will distort enough to conform, they're often "good enough". Which is not at all the same thing as "perfect" or even "correct", beyond the hold-my-beer-and-watch-this "works don't it?".

Regardless, glad you got a satisfactory result, whatever your standards for "satisfactory" might be.

 

I used stainless steel. I can still correct myself before they rust together, but for now I'm good.

 

Well then, maybe instead of the plugs' threads deforming, the plugs cut new threads in the manifolds. Butt hay, either way, if it gets your car down the road, it's all good. Even if not "perfect" or "correct".

 

Sorry, plugs are not cutting threads into cast iron. Probably requires hardened taps with cutting oil to do that.

 

Yes, something is cutting threads into something. Maybe even, both the plugs and the manifolds are getting destroyed. That's the ONLY WAY to force a mismatched object into a threaded hole.

You REALLY need to give this a rest. You graunched the wrong size hardware into your manifolds. PERIOD. Yes, it may very well "work"; yes, it may last the entire remaining life of the manifolds; yes, you may be entirely satisfied with it. THAT DOES NOT MAKE THE HARDWARE YOU USED "RIGHT". The holes in the manifolds are ½"-20 STRAIGHT thread with a 5/16" inverted flare seat at the bottom. The plugs you put in are TAPERED, 18 threads per inch, drill size 7/16" and OD of .54" at approx ½" behind the entrance. THOSE PLUGS ARE NOT THE SAME AS THE HOLES. No amount of arguing abuncha stuuuuupidity about it will change this basic fact.

As said repeatedly, just because it "works" well enough to get by, DOES NOT make it "right". No amount of your arguing will change the 18 threads per inch of the plugs you used, into the 20 threads per inch of the holes you put them into, except by one or the other distorting the other's threads.

Butt hay, either way, if it gets your car down the road, it's all good, FOR YOU, at least. Even if not "perfect" or "correct". For those of us who like our hardware to FIT rather than just JAMMING something in that DOESN'T FIT however, hardware with the correct thread pitch and design is preferred.

 

I'm going to order the inverted flare plugs, and compare them with the naked eye. Sometimes these thread counts are not percise. I did use 1/2" caps on the AIR tube,. That also fit fine as well.

 

The plugs (of the correct size) I used. I got them from Fastenal...