1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Exhaust Manifold Smog Plugs

Discussion in 'Intermediate CJ-5/6/7/8' started by FlatlanderCJ5, Mar 12, 2023.

  1. Mar 12, 2023

    FlatlanderCJ5 Member

    Wichita, KS
    Jan 2, 2022
    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.

    exhaust plug 1.jpg exhaust plug 2.jpg exhaust plug 3.jpg
    fhoehle, Fireball, vtxtasy and 2 others like this.
  2. Mar 12, 2023

    vtxtasy oldbee 2023 Sponsor

    Tucson, AZ
    Feb 5, 2006
    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.
  3. Mar 13, 2023

    amboynut Member

    Chelatchie, WA
    Aug 25, 2021
    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.
  4. Mar 15, 2023

    Dan240 New Member

    San Diego, Ca
    Dec 29, 2019
New Posts