Spark plugs

[jjjm]

Just picked up new plugs for Johnson 48SPL and Evinrude 9.9 Engines call for QL78C and QL77JC4, Shop gave me QL78YC and L77JC4, said they would work fine. Never like to change from what manufactuer calls for, just wondering what the difference is and is it a going to cause any problems?

 

[rickdb1boat]

Re: Spark plugs

Use the recommended QL78YC,as they are a bit hotter burning and will work better than the 77's. Plus, that is what the Manufatuer says to use and I would'nt vary from that.... You may want to gap them a little wider (.035-.040), if you do alot of low speed running...<br /><br />A little info:<br /><br /> web page

 

[Searun1]

Re: Spark plugs

Not meaning to hijack this thread but...<br /><br />My manual for my '81 Johnson 70 Seahorse calls for L77JC4 plugs. I talked to the fellas at my shop and they said either would work and that the QL plugs were alot more expensive. So I figured I would go with what the manual said.<br /><br />However, I have a few electronic items connected in the boat. What is the scoop on the resistor plug?<br /><br />Searun1

 

[Utah]

Re: Spark plugs

I imagine that the QL78YC plug would be the same plug for a 1980 15hp Johnson? I just took this motor out for the first time this past sunday and under full throtle it seemed like it was skipping a little bit. I was thinking this could be a result of the plugs, no?

 

[kevin Ron]

Re: Spark plugs

If you have a motor that has an optical trigger you need to use the Q plugs. The non Q plugs will run but they will mess up the spark and the motor will run rough.