Smog tubes for headers?

[Webslinger60]

(Ive got a similar post going elsewhere)
Anybody ever weld Smog Air tubes to a set of headers.

I have an 80’s carbureted vehicle that has stock manifolds with the air injection fittings.I’ve tried to run with the smog pump disconnected, but it WILL NOT pass my state emissions check without it.

I’d like to increase the exhaust performance with a set of headers but nobody makes headers with the smog fittings for my application. I know the mini-manifold-tube things are available separately. Has anyone ever attached these to a set of headers that didn’t have it? How would you do it? Drill, tap, & mount fittings in each runner & thread the tubes on? Or drill holes & weld the smog-tube-thing directly into the runners? And if you did it, did the welds last for awhile, or did they break?

[87Burb]

Hi Webslinger60. Did you ever find out anything about the scenario that you had with the smog tubes? I am into the same thing with my '87 Suburban... If you have any information could you contact me?

[Webslinger60]

I was able to find out that the Hedman Exhaust company makes separate smog tube kits.
You drill a hole in each of the header’s runner-tubes, then weld the smog tube kit to it and attach the hose to the smog pump. I bought ‘em on Ebay for $10 bucks. Now I have to find a shop who can do a real good welding job, because I fear if those welds ever break, raw exhaust flame could shoot-out and start a fire. I contacted a few exhaust shops, but they wont guarantee anything. I was then thinking of attaching those tubes using screw-together connections, like the OEM factory tubes are screwed into the GM iron manifolds. But fabricating that is even more complicated. So I put the project on hold for now.

Here’s the deal. My 1980 vehicle was designed to pass federal emissions at no more than 500 parts per million of HC. And it always did. I could even disconnect ALL the pollution equip, with the exception of the Cat converter and still pass with 475. Then about 1995, the state of NJ (where I live) decided to LOWER the minimum to 300!. After the I had to re-connect the smog pump and was able to pass at 295ppm.

But it turns out the smog pump actually does the most amount of cleaning, for the least amount of power draw. It pumps fresh ait directly at the exhaust flame, making it very hot (like adding oxygen to a welder) this vaporizes any unburnt fuel particles. It also helps the Cat converter work more efficiently too. (I also use a hi-flow performance Cat, that’s not very restrictive). And, unlike an AC compressor, the smog pump is very easy to turn. Just running that pump lowers the emissions by almost 200ppm! So if I pump fresh air into the exhaust, I can get away with neutralizing the more power-draining devices like the EGR, timing delay, lower compression, etc. So that’s why I want to keep the Air Injection System.

Ok, since my last post, I also installed a NEW 4bbl carburetor & manifold. Its one of those “50 state legal” combos from Edelbrock. I now put-out only 65ppm! I want my local private inspection mechanic to see if I can now run lower than the 300ppm minimum WITHOUT the smog pump. Then I can use the headers without having to drill them for the smog tubes. But he doesn’t want to venture to the grey area of what’s marginally legal.

So that’s where I stand so far?

[87Burb]

Great stuff! Thanks for the quick reply.

I am going to go the route that you mention with trying to locate the smog tube kit from the header manufacturer. I saw that they did have some real basic instructions in their one page instruction guide thatcame with the headers. I didn't find it very helpful but I will re-look at it.

I might also pay to have the inpsection shop do a mesaurement for me to see where my smog ppm come in at currently.

I had also not thought of going with a new carburetion system. Problem there is that my ole Burb has the TBI system and I am not looking forward to going into that...

I think I will try the smog tube route for now. I think I might be able to do the weld myself. We'll see!

Thanks again for the information.