plug question- 1996 johnson 60 hp,3cyl

[Beaux]

Previous owner had plugs that were a NGK R (BR9HS10) w/measured gap at 035. I bought champion replacements and used catalog in marine supply dealer and read to use champ L78YC gapped to 030 for my motor. I did a test run and it smoked like wet wood and stumbled at idle.. Is that champion the right plug for my motor? I think I must be crazy and somehow misread the reference chart???? It ran much better before. I am going to pull them this afternoon and recheck gap,plug wires,etc. Thanks <br /><br />Thank God I have a day JOB!!!

 

[ob]

Re: plug question- 1996 johnson 60 hp,3cyl

beaux, optional plug is QL77JC4.gap on these plugs ranges from .030 - .040.L78YC is the correct plug for your motor.Mine also uses that plug .95 70hp evinrude.Do you have vro on motor or do you mix 50:1?May not be a plug problem,but carburetion problem.

 

[Beaux]

Re: plug question- 1996 johnson 60 hp,3cyl

disconnected VRO and plugged intake hose. I mix 50:1 with 87 octane. It was fresh gas from last night and It almost sounded like it was missing and then would catch and fire all correct...kind of a surge at low rpm when in gear. I got on plane and it ran fine.

 

[Beaux]

Re: plug question- 1996 johnson 60 hp,3cyl

also, boat ran fairly well previous night with old plugs. I am leaning toward a possible bad connection within one of the plug wires when i replaced the plugs. Does that sound reasonable? Is that alternate plug a hotter plug for trolling at low speed? maybe it would be better when I troll for specs in winter. <br /><br />man, ihope I have that right.. this board always makes me nervous that I will type something stupid! Hot plug for cool engine(low RPM) right?

 

[rickdb1boat]

Re: plug question- 1996 johnson 60 hp,3cyl

Try the QL77JC4's Gapped at .040. As OB said, it does sound like it's Carurator related or too much oil in the Mix. But if all you did was change plugs and it started running bad, I would change the plugs again and try that first. Good Luck and let us know how it goes. I also have a 1991 70 HP Rude.

 

[rickdb1boat]

Re: plug question- 1996 johnson 60 hp,3cyl

Not sure if it's a Hotter Plug, And Yes, I would check the wires and replace the Plugs again.

 

[Beaux]

Re: plug question- 1996 johnson 60 hp,3cyl

I am heading home right now, will take out new plugs check gap, regap to 035 instead of 030and test motor in bay. I am also going to get your rec plug (OB/Rick) and gap to 040 and test. I will let you know tomorrow. THanks for the help!

 

[ob]

Re: plug question- 1996 johnson 60 hp,3cyl

Beaux ,doesn't hurt to play with plugs a bit to see if it improves performance.If motor runs fine at WOT I doubt if that is your problem.Check plug and coil connections as you mentioned and here's one other thing to look at.Locate the fiber cam on throttle linkage .Insure that when throttle control is in nuetral position that the roller on carb linkage is centered with scribe mark on cam and "just" touching.This insures carbs are opening at proper time in relation to timing(set at factory) and will make a significant performance difference when throttling out of hole.If it is not out of adjustment and plugs and connections don't help I'd wager you have gummy deposits in carb idle ports or idle mix screws are out of adjustment

 

[Dhadley]

Re: plug question- 1996 johnson 60 hp,3cyl

Just remember that those motors run lean in the mid range, especially on the middle cylinder. Just something to keep in mind as you experiment with spark plugs.<br /><br />I would, as mentioned, use the 77JC4's - fresh 87 octane and good oil. Make sure it able to reach 5800-6000 with an average load. Any 56 cid motor we set up also gets slightly richer mid range jets.<br /><br />Good luck!

 

[jegervais]

Re: plug question- 1996 johnson 60 hp,3cyl

Hold it guys...<br /><br />The '96 service manual AND the current BMCA spark plug chart call for a Champion QL78YC gapped at .030" - The QL plug offers a resistor/supressor feature and a slightly longer electrode. It's also 1 heat range hotter the the QL77JC4's. The combination of heat range and extended tip provide better idle quality than the QL77's.<br /><br />The NGK plugs, although they have a resistor feature, do not provide the suppression that engine's ignition system requires - Use of the NGK or non-suppression plug (i.e. L78 vs QL78) could be causing the problem you're experiencing. According to the Champion cross-reference guide the NGK plug you mentioned is the same heat range as the QL77JC4.<br /><br />I wish I had checked in a little sooner, but you really need to have the QL78YC plugs...<br /><br />-John

 

[Dhadley]

Re: plug question- 1996 johnson 60 hp,3cyl

The 78's are fine and work well but I still prefer the (small) "cushion" the 77's (cooler) offer. Especially since we dont know what top rpm is (and therefore what load is on the motor at all rpm's) and what fuel is being used. We dont know if the updates have all been done either. <br /><br />All this means nothing except this is what we do to get the 56 cid motors to live.

 

[Beaux]

Re: plug question- 1996 johnson 60 hp,3cyl

I rechecked the gap on plugs(L78YC) to standard 030. I did notice that the bottom cylinder's plug was much more fouled than others. I checked the plug wires and they appeared fine but I could not get that "snap" on the lowest plug that makes me feel comfortable knowing its got a solid connection. I fiddled with it and finally got it to gently snap on. I also went and replaced that lower plug with new. Dropped into water and VOILA!! motor ran good again. minimal smoke and no surging at low speed with WOT of 5700rpm with me/wife in 15'sport. It still idles a little erratic but better than before with old plugs. Thanks for the tips...<br />Unfortunately, i did two things so it is a bit hard to determine what was wrong. But my guess is the plug/wire connection was bad (my fault ) due to the unlikely idea that a new plug was damaged/faulty. The carb suggestions are taken and i agree it needs to be cleaned and checked to get the motor running like you guys would be proud of. I will be going thru the carb but am going to do a lot more reading and studying before that project this winter. I want to get my motor runing perfect, but I have to take baby steps. I am sure you will hear from me again when I try and summit "mount saint carburator" .... I am printing this posting to remember the carb tips OB/DHadley

 

[Beaux]

Re: plug question- 1996 johnson 60 hp,3cyl

didnt mean to leave you guys out...thanks rick and John!

 

[Dhadley]

Re: plug question- 1996 johnson 60 hp,3cyl

I'm glad you are taking "baby steps" and improving. Thats the correct way. Congrats!<br /><br />While youre looking at the wires, take a peek at the primary cnnection on the coil also. Pop it off and if there is and "gook" clean that up so the coil gets a good primary connection. Do the same with the hi tension lead and the ground. It may not improve anything right now but its a good prevent deal. <br /><br />Have no fear about the carbs. Thats one of the more basic designs and fairly simple. The manual will walk you right through it. Just make sure to use a quality kit. <br /><br />Good job!