why are spark plugs getting so hot?

[dancamp009]

I have two identical 1976 4 hp Evinrude outboards. One runs cool and one runs very hot. After I shut it down the cool one I can remove the spark plugs with bare fingers after loosening them with a wrench. On the hot one however, the spark plugs get so hot that I either have to wait a long time or use gloves to handle the spark plugs after running it for only a few minutes. Can you tell me why one runs so cool and the other runs so hot?

thank you

 

[JB]

Re: why are spark plugs getting so hot?

What spark plugs, what gap?
When was the impeller last replaced in the "hot" one?

 

[dancamp009]

Re: why are spark plugs getting so hot?

They are Champion J6C with .030 gap. I think you hit it on the impeller. I haven't ever changed it, probably is bad. I'll do that and see if it helps.
thanks alot for your help.

 

[F_R]

Re: why are spark plugs getting so hot?

I find it interesting that there is so much difference in the motors. I would expect the plugs to be too hot to handle right after shut-down. The cylinder head is not water cooled except for around the edges. They want the plugs to get fairly warm so they don't get crudded up while trolling. But still, it's interesting.

 

[JB]

Re: why are spark plugs getting so hot?

You would be better off using Champion J4Cs, Dan.