What is best way to remove heli-coils?

What is best way to remove heli-coils?


E. Tenn
1984 CJ7 258 w/T176
Not really sure where this thread goes:

I am replacing the factory plastic valve cover with a crown alum cover and it comes with 5/16 allen bolts. Problem is when I removed the plastic cover there are 5/16 holes tapped and they have a 1/4" helicoil screwed into them. What is the best way to remove the helicoil without damaging the threads. I also have the two holes on the carb side that are already drilled and I just need to tap them to 5/16.
Any ideas? Carefully drill them out? Use an easy out?


thank you.
Don't remove the heli-coil. The thread size will be wrong.
The 1/4 inch hole is 1/4-20 (thread pitch is 20 threads per inch)
A normal 5/16 inch bolt has a thread pitch of 18.
If you remove the heli-coil you will never find a 5/16 inch bolt with 20 threads per inch. Even a fine thread 5/16 inch bolt has 24 threads per inch.

The taps that come with a Heli-Coil kit are not standard taps so you can never remove the Heli-Coil and use a bolt that is one size bigger.
Last edited:
^what he said^:cool:
I put an easyout on my drill and they screwed right out. they were 5/16 x 18 thread just like normal. I ran a tap down them and they are in good shape. These were some kind of odd coils also. Another odd thing is the plastic valve cover did not have the studs on the rockers and two holes in top to secure it. It used the five bolts on the dist side/front/rear and on the carb side used very large mushroom washers on top of the head bolt studs.

On with the valve cover replacement.

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