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So I've been pondering the best way to plug the holes left in the exhaust manifolds on my Scramblers 360. That motor came out of an 83 waggy so I think it applies here. If not, someone tell me and I'll delete the thread.
Having removed and plugged the manifolds on our wagoneer, I wasn't particularly happy at how it went. I used some grade 8 bolts and had to stack washers since the holes don't have enough room in them for the shortest bolt (1") I could find that was 9/16 18. Seemed kinda butch but it did work.
So now that I am de-emmissioning my scrambler as well, I wanted something less hack looking.
A couple days ago I started by tackling trying to get the AIR tubes off. Since the bolts are hollow and the motor isn't exactly new, it is challenging. Of the 7 bolts, 5 came out with hardly any issue. Two, however, broke off in place. It's not surprising and I expected it but it still sucks.
Tomorrow I will try and tackle getting what remains out. They've been soaking in penatrant for a while but I expect I'll have to apply heat to get em free. Nature of the beast.
So how do I plan on plugging the holes? We'll, on a trip to Orileys I got to looking around. What I found that I believe will work was a little unexpected. See, the problem (to me anyhow) is that it's nearly impossible to find a really short 9/16 bolt (+/- 5/8") with fine thread 18. Nothing I looked at around town worked. Either they were course bolts or too long. As the factory bolt goes in it has a taper. That taper creates a seal to keep the exhaust going where it should, into the AIR tubes. Unfortunately it means the plug has to be less than an inch to keep from bottoming out. If you try to force it you will likely crack the manifold which is a whole different issue.
So, wandering around I stumbled on these:


Correct diameter, right thread pitch, and shorter than an inch (.377).

So tomorrow I hope to be able to test them out and report back what I find. If they work, ill let y'all know. Maybe this is the solution I've been looking for.

I don't think they have enough taper to work on their own. (Like a pipe plug). I think those were meant to be used with a brass washer but if you used some of the permatex copper stuff on the threads it should seal.

https://www.permatex.com/products/gaske ... ket-maker/

Should work - heard of using drain plugs before. I would put the proper flat copper washer between the plug and the manifold. As I recall, the original AI tubes have a copper/fiber crush washer that seals the tube to the manifold - no taper.

Price on these varies a lot. RockAuto has them for $2.93 ea - your local parts store should be able to match that. Some online sources are $15-20 each.

$15-$20 ? That sounds like BMW prices

Oops... I should have added that I did pick up some 9/16 copper washers. I plan on using copper anti-sieze on the threads before installing the bolt/washer.
Unfortunately, I won't be able to mess with it today because I'm pressed for time. Have to turn in school work so I graduate early thanks to an Army commitment. Hopefully tomorrow I can tinker.

Ace Hardware(here anyway) had allen head plugs that worked for me.

Like this...any good hardware store can get ‘em.
Big flat head seals well.
https://www.shopcross.com/product/parke ... gI-gPD_BwE

I’ve also used regular 9/16” bolts cut to size as well, only takes ~10 minutes to slice down a set.
The drain plugs will work fine too, kinda silly spend 3x $ though.
I’ve never used sealing washers, no leak issues.

As a last resort, spark plugs that fit the AMC engine are the same thread...

XSAPPER have you tried them . I purchased 10 and they are a loose fit I hope they work .

fsj454 wrote:XSAPPER have you tried them . I purchased 10 and they are a loose fit I hope they work .

No I was going to order some for my sons 79 J10. Maybe I should go another route.

I just put bolts in mine. The taper makes them get tight before they go in all the way, but they don't seem to leak at all. The real pain was getting the rusted out air tubes out of the manifolds as I was not able to fit a drill with reverse cut easy-out on all of them.