Spark Plugs for 1977 Johnson?

[csgrizz]

Can someone point me in the right direction on spark plugs for my 1977 Johnson 25 hp?<br /><br />I got the "slipping" issue fixed and it was indeed a bad prop.<br /><br />The plugs that are in it now are splitfire, never seen that in an outboard before, but they definitely need replaced.<br /><br />Thanks,<br /><br />CS

 

[Joe Reeves]

Re: Spark Plugs for 1977 Johnson?

Use either Champion QL77JC4 or L77JC4 plugs, gapped at .040 . The "Q" is a supressor plug that is designed to help quiet noise/interference in any electronic equipment you might have aboard.

 

[Roj115]

Re: Spark Plugs for 1977 Johnson?

Get the NGK equivalent to the Champion. I've used both kinds in my '74 Johnson 115 and '77 Evinrude 9.9 both of which I've owned and maintained since they were new and I've found the NGKs to be much better and durable than the Champions.<br /><br />I think the NGK is a BPR9ES 10 or something like that. Just go to a NAPA and tell them you want the NGK equivalent to the Champion QL77JC4 or L77JC4 and they will look it up in their books or computer and give you the right NGK.

 

[Roj115]

Re: Spark Plugs for 1977 Johnson?

I gotta disagree. Just because OMC specified Champions when they made the motor doesn't mean there isn't something better on the market now or even that there wasn't anything better on the market when they made the motor. It only means Champion won the contract to supply them with spark plugs.<br /><br />I used Champions for about 15 of the 30 years since we got the '74 Johnson 115 new and the other 15 I've run with NGK. When I put a brand new set of Champions in at the beginning of the summer (gapped at 0.040") I can see the electrode is worn (noticably tapered) at the end of the summer when I pull the plugs out to winterize the engine. So I chuck them in the "old spark plug bin" and use them only for winter storage plugs. With the NGKs, however, I see no such tapering or wear even after the second or third summer of use. <br /><br />I've also used the NGKs in my '77 Evinrude 9.9 which I've also had since it was new. Up until about 1990 I used Champions in it but since then I've used NGKs and have found them to be a noticeably better and more durable plug in that motor as well.<br /><br />So I wouldn't place much importance on what type of plugs the motor came out of the factory with or what brand they specify in the owner's manuals. It doesn't mean the motor was designed around those plugs or that brand plugs are the best for that motor. It only means Champion was able to provide a line of plugs that met OMC's specifications at the cheapest price and became their supplier. Or maybe it just means that the CEO's of both companies went to the same Ivy League school or are members at the same country club.<br /><br />So my experience has been that NGK plugs work noticeably better and last much longer than Champions in both of my outboards. The only way for you to know which is better is to try one brand out for a year or two and try the other for a couple years and see which one works the best for you and go with that one. FWIW I'm going with NGKs in my two outboards.<br /><br />Roj

 

[walleyehed]

Re: Spark Plugs for 1977 Johnson?

3128 is the Wiseco piston P/N if you are going to use NGK...You will need the pistons sooner or later...been down this road too many times.<br />QL82C is the most recent Champion P/N you want.<br />Book says .030 gap, but if you troll alot go to .040<br /><br />EDIT: Roj115, the Johnson/Evinrude engines WERE designed to use ONLY champion plugs, and this is known industry-wide by the top wrenches.