Exhaust Manifold Smog Plugs

This may be an old technique for some of you but I pieced the info together from some other AMC forums. I bought some used exhaust manifolds that still had the smog equipment attached. When I removed the bolts, about half of them snapped off. I got a few of the broken ones out with an EZ out (never easy- rarely out). I don't have a torch hot enough to get it glowing red and then try the easy out again. I took it to several welding shops and nobody wanted to do it, too small of job I guess? So I tapped the broken ones with a 3/8 coarse tap and installed flange head bolts. To make them all match, I took some old spark plugs, Autolite 65, and they are the exact threads of the smog bolts. As you can see, I removed the porcelain insides, threaded it in, ground it flat and ran the 3/8 tap through it and installed new bolts. The tap fit perfectly with no drilling of the inside. I think I will still put a small divot near the edge of the bolt head flange and stake the bolt to help prevent it from backing out. Had all the smog bolts come out, I just would have bought the plugs and left it at that, but at least now they all match. Hope this helps someone.

 

Creative but not a tapered thread. It may leak a little and I am not sure what would seal at those temperatures. I suppose you could try some teflon
on the threads. I wouldn't hurt and has no where to go. A better option with the flange head bolt would be copper washers used for flange connections.

 

Years ago on an Isuzu engine I just screwed spark plugs into the holes and called it good. Never failed to start a good conversation.

 

There are several places that sell plug kits. Here is one:

https://www.bjsoffroad.com/AMC-V8-Exhaust-Manifold-Emissions-Port-Plug-Kit_p_2000.html