spark plug question

[THEFERMANATOR]

OMC released a bulletin back in the early 90's to supercede teh surface gap plugs to the QL77JC4 gapped plugs due to the tendancy of surface gap plugs to foul out during extended idling. If you're after max performance and run at sustained high RPM's(5K+ RPM's) stay with the UL77V surface gap plugs, otherwise switch over to the QL77JC4's and enjoy better idling and low RPM performance. I avoid the QL78YC's though as I have found teh extended electrode plug to not perform as well down low.

[mushman]

Thanks, I rarely ever run at 5000+, and the idle is a little rough so maybe I'll give the JC4's a shot and see how she runs.

[csvencer]

Originally Posted by THEFERMANATOR

OMC released a bulletin back in the early 90's to supercede teh surface gap plugs to the QL77JC4 gapped plugs due to the tendancy of surface gap plugs to foul out during extended idling. If you're after max performance and run at sustained high RPM's(5K+ RPM's) stay with the UL77V surface gap plugs, otherwise switch over to the QL77JC4's and enjoy better idling and low RPM performance. I avoid the QL78YC's though as I have found teh extended electrode plug to not perform as well down low.

Damn, I just put QL78YC's in yesterday. 1999 Johnson 175. What should I have gone with?

-Svence

[THEFERMANATOR]

Originally Posted by csvencer

Damn, I just put QL78YC's in yesterday. 1999 Johnson 175. What should I have gone with?

-Svence

The QL78YC's will work fine, but they do tend to foul a bit easier than the QL77JC4's do at idle and trolling speeds. I know the QL77JC4's are getting harder to find though.