Smog "tubes" in exhaust ports

[JohnnyO]

Are the smog tubes in the exhaust manifold supposed to be ceramic coated or do mine just have buildup on them?

I am asking because I want to blast it and need to know if I should protect them.

TIA

John

[280~Master]

No they were not like that from the begining. Do you have a picture?

[JohnnyO]

Here is a picture of the header with the smog rail installed. You can see the white buildup on the steel tubes that go into the exhaust ports. I hit one of them with a wire wheel and it "dusted" off about 2 MM of white powder which made me believe it was ceramic.

Any idea?

John

Edited March 14, 2009 by JohnnyO
Added another picture

[zbane]

IMO, it's just buildup. Why not spray the tubes with a safe cleaner (simple green comes to mind) and just try cleaning them up a bit?

[Arne]

Don't breathe it in - I suspect the white stuff could be lead buildup.

[manny1973]

I have removed the air tubes from my manifold. After using Krol they just unbolted. The tubes that go into the head as shown in the picture (Johnny'O's) are still there. Should I take them off or just leave them. If I should take them off what is the best way?

Edited December 7, 2009 by manny1973

[esprist]

I have removed the air tubes from my manifold. After using Krol they just unbolted. The tubes that go into the head as shown in the picture (Johnny'O's) are still there. Should I take them off or just leave them. If I should take them off what is the best way?

What I recommend you is to cut right at manifold for better performance with all the original parts on it. (If you unbolt the tubes, you still have to plug them anyway.) Now you could still run air pump with all the emission stuff on the car.

Esprist

[Walter Moore]

Don't breathe it in - I suspect the white stuff could be lead buildup.

Yes it is almost certainly old lead anti-knock compounds. But wow, to have a header in that condition that is old enough to have seen leaded gas... that has to be a collector's item.

Most of the headers I had on daily drivers back when leaded gas was still legal typically didn't last more than about 2 years.

[manny1973]

Is it Ok to remove the tubes from the manifold that go into the head or should I just leave them?

[JohnnyO]

Manny, It looks like esprist has suggested just cutting them flush with the manifold. In my case they were bolted into the header just as they would with an exhaust manifold and I left them. I have the original manifold and on the next head gasket blowout I plan on replacing my E88 head with one of my E31 heads and the original manifold to get it all back to stock.

I am not exactly sure of the purpose but I am pretty sure it had something to do with getting the leftover "smog" deep enough into the cylinders to effectively burn it. With that in mind, you probably wouldn't hurt anything by cutting them down and even welding them shut. This would give you a stock look with less of an impact from the smog gear. Maybe someone a little more familiar can chime in on the functionality of them.

BTW, on the recommendation of posters to this thread I did clean them up. I blasted them while I was blasting the rest of the header. And yes, I was wearing a respirator.

Edited December 16, 2009 by JohnnyO

[JohnnyO]

Yes it is almost certainly old lead anti-knock compounds. But wow, to have a header in that condition that is old enough to have seen leaded gas... that has to be a collector's item.

Most of the headers I had on daily drivers back when leaded gas was still legal typically didn't last more than about 2 years.

When I purchased the car last September it had been sitting since 1989. In the reciepts I received with the car (every reciept since new) I found the invoice for the exhaust system from F.A.R performance and it was dated 1986.

Being that it was a California car I would imagine that the smog rail was moved over to the new header at that time. With most cars since 1975 having Catalytic Converters installed I would imagine that leaded fuel in California was not available by the time this header was installed but the smog rail was probably original and the white buildup was probably from the early 70's.

The odometer difference between the 86 invoices and the last oil change in 89 was only 8000 miles.

John

[SeafireXV]

Even though this is an old thread I'll add my comments for any curious readers. Those tubes are for the air injection system for the smog setup. The trick thing to do back in the 70's was to lightly tap them out with a hammer and then re-attach the air injection rail, if you were staying with the stock manifold. With a header as in the picture they should have been left off. Either way will help the exhaust flow while still allowing the smog setup to work a bit, if that's what you need. Don't worry about the carbon buildup, it should flake off as you push them through the holes. I don't think that there is any "lead" buildup, since leaded fuels have'nt been available for 25+ years. Just be sure not to pound on the tube too hard or you may distort them and you'll have to cut them off.