Damaged spark plug threads

29restorod

29restorod

Senior Member
I had trouble starting the threads on a new Champion W18 plug,in my Simmons head. I am always careful to make sure they go in with fingers only,before torqueing. After inspecting the threads in the #4 hole,I found them about 50% gone. Is there a repair kit for the large size plugs? I would like to just fix the one hole to original size.
 
I agree that a machine shop could do the work and give you peace of mind that it is done right. I've used Helicoils in different instances, but wouldn't want to try to repair a spark plug hole. Hopefully the repair can be done with the engine head in place, although probably best with the head removed. Let's hear what the others say about this. CC
 
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California Charlie said:
I agree that a machine shop could do the work and give you peace of mind that it is done right. I've used Helicoils in different instances, but wouldn't want to try to repair a spark plug hole. Hopefully the repair can be done with the engine in place. Let's hear what the others say about this. CC
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Worst case would be if the car can't be taken to the shop, the head would have to be removed. But, since it is #4 the head might have to be removed anyway. Personally I would rather take the head off for the work to be done to ensure no chips or shavings in the cylinder. (assuming a helicoil can be used, of course)
Ed
 
I think that a thread insert would be a better fix for damaged spark plug threads. I found an E mail address in my notes for thread inserts. Here it is. sales@ ababaqa.com I don't know how long this has been in my notes, Won't hurt to try. I had a repair like this performed on a power saw head years ago. The head will have to be removed and any good machine shop can make this repair.
 
Check with your closest car dealer service dept. Stripped plugs are not un common and they should have a soure for repairing them. The guy I have used out west has a mobile business and can bring his services to you.
There are better choices than helicoils.
 
I am glade to know that there are options for the large size plug. When I worked on VW's,it was champion plugs that seemed to strip the threads most of the time. If you look at the threads of a Champion plug,they look ragged like a saw,because they are lathe turned. All other plugs have rolled threads,and they have smooth edges. An old saying is "anyone can install Champion plugs,but no one can remove them". I have avoided them for 40 years because of that. The thread damage in this head was done before I got it.
 
the only inserts i will use are "timeserts"
they are one piece not a coil of wire
ive used them on head bolts torqued to 65# and they work great
 
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