Plug your GM A.I.R. manifolds
GM Corvette/Camaro exhaust manifold with A.I.R. Smog
Easy Instructions -- How to plug ports with brass:
Friends frequently ask what I recommend doing to plug their smog manifolds to make the A.I.R. system non-functional.
I prefer to use this method rather then simply blocking the ports with nails or screws.
This brass plug method is "permanent," but easily reversible.
I really believe we are only curators of these collectible cars, and we should preserve them as best we can for future generations.
If you are starting with a clean and rust free manifold, this modification can be accomplished in about 30 minutes per side.
Using a brass plug insures that these A.I.R. ports can be returned to original configuration, even 100 years later with no permanent damage.
These manifolds were originally bare metal (natural finish), installed at the assembly factory; no paint was used on them.
Some manifolds which had been installed at the engine plant, could have been “oversprayed” engine color.
After cleaning, use either a high-temp clear, or a cast metal color for the most authentic look.
The items you will need: 1/8” pipe thread tool, 8 ea-1/8” brass hex head pipe plugs, hex hand wrench, small hammer.
Pictures 2 & 3
Remove the external tubes from your exhaust manifolds, and push out the small internal air extensions inside the ports.
Push them out from the back with a hammer.
These small tubes are readily available, and cannot be seen when installed.
If they are damaged, discard them, otherwise save them with your other parts to stay with the vehicle.
Pictures 5, 6, 7
The holes that the tubes came out of are exactly the right size for a 1/8” pipe plug.
Use your 1/8” pipe thread taper to thread the smaller hole way down inside.
Do this from the front, using the larger hole as a guide to keep everything straight.
Thread the entire way through, but don't go too far, because you want the plug to sit at the bottom of the hole.
If the tap peeks through about 3/8”, that is enough.
Use plenty of cutting oil, and clean your tool frequently.
Do this for all eight of the A.I.R. ports.
Pictures 8 & 9
Coat the plug-threads in red Thread Locker or Loctite, and install them down in each port from the front.
Make sure they sit properly all the way down inside the openings.
If you are forced to use the square-head plugs (available from Home Depot),
you will need to tap from the back and inset from behind, in order to leave room for the tubes in front.
I like to use a internal hex plug found commercially.
Install your tubes back over the top of the plugged ports; no one will ever know they are plugged.
You should be able to tighten down normally as if nothing had been changed. You are done - enjoy!
With a little patience, this is a very easy thing to do. Hope my instructions are helpful to you.
Jeff's 1969 Camaro IPC - with non functional smog system.
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