Correct spark plug

[wrj9892]

I have a 1979 Evinrude V6 150. I am getting ready to change out the plugs because they show signs of wet fouling. The currect plugs are L77JC4. The manual says to use UL77V or QUL77V. What is the difference?

 

[rickdb1boat]

Re: Correct spark plug

UL77's are for high speed running. QL77JC4 or L77JC4's are for all around use. UL's are a surface Gap plug, meaning that they do not have an electrode on the end to Gap. They just fire from the center of the plug, which is flat on the end. I would stick with the QL77JC4's and Gap them at .030! They tend to do better as an all around plug. Less fouling at idle, too. I tried the surface Gap plugs a while back and did not care for the way they operated a low speed and idle(Rough).

 

[wrj9892]

Re: Correct spark plug

Thanks Rick.