plug ports

[Cobbie]

hi i have a evinrude big twin 40 what i need to know is wht is the plate called where the spark plugs fit in to it has numerous screws holding this late on my problem is is that ive lost the threads off one on the ports where the plugs seat in to help is most welcome

 

[rickdb1boat]

Re: plug ports

That would be the cylinder head. Remove it and take it to a machine shop where they can install a helicoil insert for the plug. Good as new. Replace the head gasket when you put it back together and torque the head bolts properly.(Don't know the torque on those, but someone will... )

 

[Silvertip]

Re: plug ports

It's called a cylinder head. The spark plug hole can be repaired with using what's called a heli-coil. If you are unfamiliar with these you should have a shop do the job.

 

[Cobbie]

Re: plug ports

Thank you for your quick reply... most greatful d

 

[clint]

Cylinder Head Port

Cylinder Head Port

I had it done on my 140 Evinrude. They drill out a larger hole to alot for new helicoil, which is a new thread will be installed for standard (stock) spark plug that it will fit into. It will be as good as new. Just make sure to go easy on future removal and installation of spark plugs, more on the tightening. Good Luck!
Clint 8)

 

[OptsyEagle]

Re: plug ports

I have a 9.9Hp Evinrude (1975) that has those heli-coils installed, however, on the bottom cylinder it has unscrewed out of the plug hole a little and has been bent from a spark plug. Perhaps it was tightened too much.

I now worry about getting a proper seal on the plug, but I cannot see smoke or anything coming from this plug hole when the engine is running and the engine seems to run OK.

My question is, can these heli-coils be easily screwed (or pushed) back into the threads. I gave this an initial attempt but found it difficult to get a grip on it (using needlenose plyers) and since the material is so thin, I worried about breaking it off.

Any thoughts would be appreciated.

 

[rickdb1boat]

Re: plug ports

You may want to get a helicoil extraction tool and remove that one and install a new one...They are basically held in place by outward pressure(Spring tension) and once they lose their pressure, it can be difficult to keep them from turning out...

 

[JB]

Re: plug ports

Helicoils are fine for repairing holes in iron or steel, even aluminum alloys that don't have a heat transfer function.

In an alloy cylinder head the steel helicoil does not transfer heat from the plug to the head the way the designers intended. Consequently the plug is hotter than intended. Because your engine already uses the Champion J4C (replaced the J4J) there is not a cooler plug to switch to.

Those plug holes should be repaired with an aluminum sleeve called a "Time-Sert", which is installed much like a helicoil. That will give you the designed heat transfer rate.

I guess from your atavar that you are in the U.K.. Check around for a shop that can install a "Time-Sert" for you.

 

[Cobbie]

Re: plug ports

hi again ive just had a quote on doing the job for me which is quite reasonable £35.00 thanks again for all your advice