What's the difference in these plugs?

[gsbodine]

I've had the L77JC4's in my motor and went to get some more the other day. I looked in my manual and saw that the recommended plugs for the larger motors (starting with mine, a 1978 Johnson 150) are UL77V's.<br /><br />Everything has seemed fine, more or less. No problems I could attribute to spark plugs anyway . <br /><br />What's the difference between these plugs? Hotter or cooler or what?<br /><br />Advance thanks for the enlightenment.

 

[Barnacle_Bill]

Re: What's the difference in these plugs?

The UL77V is a surface gap plug. Another words, you can't adjust the gap. Not sure about the heat range, but I would use what is recommended.

 

[walleyehed]

Re: What's the difference in these plugs?

The surface gap plug is for engines that seldom see alot of trolling speeds or may spend alot of time idleing. The QL77JC4, or the newest recommended plug, the QL82C would be the best choice for trolling or extended idle periods.

 

[Walker]

Re: What's the difference in these plugs?

I've never had satisfactory results from surface gap plugs on either OMC or Mercury motors. Short life being the main complaint.

 

[gsbodine]

Re: What's the difference in these plugs?

Thanks, guys! I had been running the QL77JC4's at .030. Will continue doing so.<br /><br />thanks again for the comments.

 

[jimmbo]

Re: What's the difference in these plugs?

I used the surface gap plugs in my motor for 14 yrs of moderate to heavy useage without changing and never had trouble. The plugs were still firing when I traded it in. Maybe the fact they were NGK had someting to do with it.

 

[walleyehed]

Re: What's the difference in these plugs?

14yrs puts a tremendous amount of resistance on the ignition system, and would show neglect, in my opinion..<br />J/E are not designed for NGK, and I would say you are a lucky one....hope I never buy that engine used..it has little life left.

 

[jimmbo]

Re: What's the difference in these plugs?

It was a Merc that's why it had NGKs in it from the factory. As for neglecting my motor? Not so, I checked the plugs visually regularly, and hooked it up to my scope and the voltages and rise times were always good. They were good plugs. From what I've heard, It is still runing strong, and I traded it 6 yrs ago.

 

[Roj115]

Re: What's the difference in these plugs?

My '74 Johnson 115 was supposed to have the rimfire gapless plugs but they kept fouling up and a Johnson mechanic told us to switch to the QL77JC4s (regular type plug) and they worked much better. About 15 years ago I switched to the equivalent NGKs and they were way better than the Champions. They seem to be more reliable and they definately last a LOT longer than the Champions. I use the same NGKs in my '77 Evinrude 9.9 and I recommend them for those motors as well.