Spark Plug Thread Repair

[Garys1969RR]

Well I hate to admit it, but last night I was tired, and the last spark plug I put into my alum heads got cross threaded! I didn't run it in but about a turn and a half before I realized my mistake, but the threads were damaged. Couldn't get it started straight this morning, so I found a new tap, 14 MM by 1.25 MM thread pitch at O Reilly! I was happy to find one. After removing the other 3 plugs and the headers, I was finally able to run the tap in which made the threads straight, and I was able to put the #6 plug in. I know to thread the plugs in by hand at least several turns, before putting the wrench on, which is what I normally do. I tend to make mistakes when I'm tired. I have had trouble on # 6 cyl on big blocks. My first 383 burned oil only on # 6 cyl! Oh well, hope this keeps someone else from making the same mistake. Does anyone else have an easy repair for cross threaded alum threads? I think this happens once in awhile, because that tap is readily available at auto parts stores.

 

[BeeKool]

Tap is the easiest method. Doesn't hurt to clean the threads when you have the plugs out .I have a thread chaser from Jegs that I use. It doesn't require you to remove manifolds/headers.
I've know people who have had to use Heli-Coils on heads that they've damaged.
Sounds like yours wasnt damaged badly

 

[Fran Blacker]

Having that happen really sucks.

 

[Forklift]

I repair spark plug hole on a lot of forklift heads. The time-sert kits work the best. You don't have to remove the head and it installs a solid bronze insert. I hope this will help.

 

[bm02tj]

If you grease the tap to hang on to the cuttings all the better

 

[miller]

Too bad the makers of aluminum heads don't install steel threaded inserts for spark plugs. Aeroplane cylinders have 'em.

 

[not so famous bob]

Too bad the makers of aluminum heads don't install steel threaded inserts for spark plugs. Aeroplane cylinders have 'em.

# 5 is the bitch on the raised port heads in my 68 barracuda. I bought a tread straightener at jegs that goes in, expands, then you back it out. is a little of a pain to get tight and started straight when its so tight w/ the steering column there , but a little patience and it works. had to run it out a couple of times to get the threads right . brings all the material it cuts out of the head since your screwing it out. just be careful to get it in the threads straight when tightening down to come out.

 

[mentor70]

if you have really messed up, a time sert is the best and most perminet way to repair it.
https://www.mechanicstoolsandbits.c...p2rTyISbLm7C8deq3WV0Tjm8DjU8jq1tFkaAle48P8HAQ

 

[brian6pac]

I have done a hand full of 5.4 fords, apparently they don't like spark plugs and spit them out often.
I'm with bm02tj, pack the tap with grease and it will hold all the chips install the insert and your good.

 

[Glenwood]

Same on my boat's merc. This tool saved my butt.

 

[BeeKool]

I have done a hand full of 5.4 fords, apparently they don't like spark plugs and spit them out often.
I'm with bm02tj, pack the tap with grease and it will hold all the chips install the insert and your good.

Do you know of any 5.4 Ford that doesn't have at least 1 plug hole repaired?

 

[Garys1969RR]

Same on my boat's merc. This tool saved my butt.
View attachment 390266

Wow that looks like the way to go! Thanks for all your replies! Looks like running the tap in there fixed it. Spark plug is in there, and I'm not taking it back out for awhile!