HeliCoil Size Double Check

[sturgeon_general]

"I wasn't able to locate t

"I wasn't able to locate the original helicoil spark plug rethread kit.All I could find is a company by the name of Perma-Coil thread kits(spark plug).I purchased the kit with 14mm x 1.25mm x 1/2" spark plug inserts.I was told by the salesman, once the insert is installed it is permanent.So I thought I"d double check before I preceded with installation.This is for a spark plug rethread on a 1983, 35HP,Johnson,model no.#J35 RCTS,Thanx,The Sturgeon General."

 

[joereeves]

"I just took a look at the Per

"I just took a look at the Perma Coil kits and they seem to be identical to the heli coils that I've used for years.

Now, that being said..... some cylinder heads have the spark plug thread reach to be 1/2", where other heads might have only a 3/8" reach.

Check the depth/reach of the threads. You do not want to install a 1/2" deep coil into a spark plug hole that only has a 3/8" deep reach. It stands to reasopn that if you do, 1/8" of that coil will be within the combustion chamber.

I have, in the past, when faced with a 3/8" deep threaded hole and only having a 1/2" heli coil, I would simply cut off enough of the coil to reduce it to a 3/8" heli coil. Works for me.

Let us know how you make out."