Alternate plugs for a '76 115

[Cricket Too]

Just got this '76 Johnson 115 and it has the NGK equivalent of the Champion UL77V in it. I'm gonna replace with Champions but wanted to use something other than the surface gap plugs. I know I can use either QL77JC4 or L77JC4, but just want to know what the difference between the two are, is the QL a little hotter or vice versa? Is there any reason not to put the UL77V's in, I don't particularly like the surface gap, just because I like to set my own gap to .040, but is there any reason these engines use the surface gap plug. Also (and I know I'm gonna get crusified for asking this) is there anything wrong with the NGK plug? I know OMC's are designed for Champion, but the shop I bought the motor from says they only use NGK, and they are a pretty reputable OMC place in the area. Thanks for the info, Mike.

 

[Dhadley]

Re: Alternate plugs for a '76 115

If that shop is that good with OMC motors they should know the carb'd motors should use Champions only. Ask them to show you in an OMC or BRP book that its OK to use NGK's in that motor.<br /><br />The Q is for the suppressor type plug. Helps to eliminate RFI interference. Both are the same heat range.

 

[Cricket Too]

Re: Alternate plugs for a '76 115

Thanks Dhadley. Yeah when they said they only use NGK's it made me a little nervous. Is there any advantage to using an L77JC4 over a UL77V in this motor? Is there any disadvantage to using the surface gap type?

 

[Dhadley]

Re: Alternate plugs for a '76 115

Yes. Money.<br /><br />Either plug is a good choice but I use the 77's because I've never seen any advantage to the surface gap plug. We ran the gapped plugs in the race motors for the same reason.

 

[Cricket Too]

Re: Alternate plugs for a '76 115

OK so I'm guessing then that by 77's you mean the L77JC4 and not the UL77V. Just for my own personal info, what is the problem with NGK's? Is there anything specific or just that OMC's were designed using Champions? I mean I always use Champions in my Johnrude's and always will, but am just curious as to what the deal is with the NGK's. Not nitpicking, just for conversation and my own personal knowledge. Thanks, Mike.

 

[Dhadley]

Re: Alternate plugs for a '76 115

Sorry about that! Yes, the QL77JC4 or the L77JC4.<br /><br />Sometimes the crossover between a Champion and an NGK is not exactly direct. The NGK's tend to burn a bit hotter. Now, that doesnt mean that something bad will happen every time you use them but it can. Certian motors are more prone to issues popping up than others. I have seen certian OMC motors that burned a piston and the only variable was the different plugs.<br /><br />For example -- a particular guide here in Florida uses his boat about 6.5 days a week. Every week. The guy just doesnt care about weather. Anyway, he had an OMC motor for about 3 years. No telling how many hours he had on it. The bottom line is that obviously the fuel was fresh and everything else was as it should be. All he did was put NGK plugs in it one day. It made it about 2 miles. Burned a piston. We rebuilt it and installed Champion plugs. The water pump was less than 3 months old so we didnt change it. I wanted to, he didnt. But the motor had no cooling issues when we saw it to begin with. We know he ran the motor for at least 2 more years. <br /><br />Now, NGK's arent the only plug we've seen in this scenario. Nobody's picking on NGK. In fact I'll bet you'll hear Yamaha and Merc guys cuss Champion. They foul easily in those motors. Those were made to run the slightly hotter plugs. You install the cooler Champions and they foul easy and naturally its the plugs fault. Burnn a piston and its the motors fault. Go figure.<br /><br />Then, we're not saying we've never ran NGK plugs in our motors. In some race motors we need the hotter NGKs. But with certian race motors we dump tremendous ammounts of fuel.<br /><br />Also, we've set up stock rigs that the guy insists on using NGKs or Autolite or Nipendinso or whatever. And doesnt want to believe that the burned piston (he just paid to replace) was a result of spark plugs. So, we richen up the mid and hi range slightly to bring the combustion temps back in line and bingo! No problems. And naturally he insists the jetting had nothing to do with it.

 

[Cricket Too]

Re: Alternate plugs for a '76 115

Great explanation Dhadley, thanks for the info and the help. Appreciate you sharing your knowledge. Thanks again, Mike.