C-3 Exhaust Manifold Inboard AIR Tubes

[Egil Askeland]

I am refurbising my 1969 L36 exhaust manifold (3880828-RH).
Is there a good method for removal of inboard AIR tubes without damaging these?
Are new tubes available trough GM, - part # ?
Thanks, - Egil

[Joe L.]

Re: C-3 Exhaust Manifold Inboard AIR Tubes

Egil-----

I wouldn't worry about damaging the tubes; I'd worry more about damaging the exhaust manifold trying to get them out. Usually, these tubes are heavily encrusted with inorganic combustion deposits. I recommend trying to break away as much of this material as possible with a chisel or similar tool. When you get it down to just a little, use a wire wheel on a drill to finish it off. Then, you should be able to drive out the tubes (from the inside out) with a mallet without using too much force.

The original big block tubes were GM #3882805. These were discontinued quite a few years ago and replaced for SERVICE by the small block tubes, GM #3877484. These tubes are a little bit shorter, but will work just fine. They're still available from GM. That's the good news. The bad news is that they currently GM list for $18.21/EACH. That's primarily because these tubes are made of a special alloy steel with high nickel, chromium, and cobalt content in order to withstand the heat involved. The tubes are also available for both big block and small block in reproduction from suppliers like Dr. Rebuild. They cost about $80 for the engine set.

[Joe L.]

Addendun

I should also have mentioned that the tubes are usually not suitable for re-use. I think that you will find that when you get all of the combustion deposits cleaned off that the inner ends, the tubes will show serious signs of material "erosion". Some folks feel that you can still use the tubes or, even, just leave them out altogether. I DON'T feel this way. If the tubes were totally superfluous, GM wouldn't have put them there in the first place. Bet on that!

[Stephen W.]

Re: Addendun

I've modified a small "dent puller" with a hooked wire attached. This is not a piece of flexible wire but a piece of steel fashioned to form a hook small enough to slip inside the tube. I must admit I did this on my 1969 Z/28 back in 1973 so it didn't have a lot of deposits on them. Sunoco 260 was still available and it was at 38.9 a gallon.

[dick foehringer]

smog inside tubes

i just pounded out all 8 of mine and im not going to use them. bent 2-3 of them but the others are good. let me know if you are interested. mine are suity but no erosion.
regards dick

[Egil Askeland]

Re: smog inside tubes

Dick, - yes I would be intrested in some good ones. By the way, did you ever need to or try to replace stud bolts at the exhaust pipe connection end of the manifold? Mine are severly corroded and I am concerned about how to safely remove the remains if I brake the stud during my attemt to remove these.
Thanks, - Egil