spark plug threads

[tjizzle]

I have a 1978 70hp evinrude. Was getting water in cylinders I replaced head gasket and exhuast manifold gaskets fixed problem. Took boat out last weekend ran great when i got home i went to put some new plugs in and top plug threads are stripped. I get a helli coil kit and pulled head back off and installed helli coil put plug in and seems like helli coil is stripping. I hand tightened spark plug and as soon as i put socket on it it will snug up and and keep turning. The torque in manual says 17.5-20.5 ftlbs cant get anywhere near this. Does any one have any suggestions on another way to fix this or do I need to get a new head. Thank you for any imput.

 

[retiredfornow]

Re: spark plug threads

I heard that these were good, but I have no experience with them. Looks like they would work.
http://www.timesert.com/

 

[RZR2007]

Re: spark plug threads

Is the Helicoil turning out of the head as you tighten the plug up? I've seen this sorta thing when a regular tap is used instead of a helicoil tap, there is a difference. May need to pull the helicoil out and replace it, the're pretty easy to get out , if you can get ahold of the end of it...

 

[gransee]

Re: spark plug threads

The same thing happened to my motor last week. I put a heli coil in it too and thought the problem was fixed. Turned out i was loosing compression in the cylinder with the stripped plug hole. I could hear air coming out the spark plug hole when i would turn the fly wheel. this was after installing the heli coil. I ended up buying a used head off ebay for $35 and a new head gasket and walla... problem solved. Wish i would have done that right away instead of horsing around with the heli coil. Good luck

 

[tjizzle]

Re: spark plug threads

Thank you for the responses. I did use the helli coil tap that came with it .