spark plug heat range

awthacker

awthacker

Junior Member
A neighbor recommended that I go to the next hotter plug than what the engine specs call for, because I am pre-mixing and my oil ratio is rich. Says it may help the engine run more efficient and keep the plugs cleaner from fouling. Do you guys agree?

Also, he recommended I switch from Champion to NGK. Engine is a 1994 Evinrude 175 HP two-stroke. I'd be glad to here anyone's opinion on plugs for this or similar engines.

Thanks,
Aaron
 
I wouldn't switch to NGK's unless you want problems. OMC's always seem to run best on CHAMPIONS(at least for me anyways). Your engine calls for 2 different plugs depending on useage. The QL16V is a surface gap plug and is best suited for high RPM running. The QL77JC4 is a great all around plug, and is about all I use in them. Many will run QL78YC's, but I have found them to foul at idle alot, but work great in the higher RPM's.
 
I can't answer the hotter plug question.

But the NGK vs Champion I have some experience with. I had a Yamaha IT 200 dirtbike that would foul the NGK plug EVERY cold start.

Switched to Champion, never had one foul again.
 
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Gotta jump on the Champion bandwagon. I have had nothing but problems with NGK and fouling. Champion just seems to work better in every engine I've put them it, be it snow blowers, chain saws, outboards, or vehicles.
 
I hate Champion plugs, years ago when I worked on cars, it was not uncommon to get two bad champion plugs out of a pack of four plugs. Since i started working on boats, I started using NGK. I have never(26 years) run across a single NGK plug that was worn out. I've seen them fouled by gas, oil, and water, but never worn out. If you ever drop a champion plug(non copper core) it usually breaks in half. I've tried to break a NGK and all they would do is break the porcelain off and bend over. Ive run back to back test with Chanpion vs NGK plugs in a 225 looper and made more power with the NGk on a K&O dyno(yes, i know they don't recommend anything but Champion due to electrical interference). Champion plugs rust quick in a salt environment compared to NGK or AC(autolights are the worst about this). Champion plugs run like crap in a 2.4/2.5 merc(run good in a 3.0L).

But even after all this, I'd have to agree that in some motors(mostly OMC) Champion seem to run better. Run the projected tip plug that Ferm recomended
 
I don't know Jack Chit, but I've always run Champions in the old Johnson/Evinrude stuff like I'm told to.

I've noticed a lot of Japanese stuff runs the NGKs.

I have Bosch and NGK in my 2 stroke lawn equipment and the Bosch seems to foul a lot. Never had an NGK foul.
 
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I just put the champions back in... The std low-cost one l77jc4. Not looking to drop $50 on plugs.

So it's pretty unanimous that going to a hotter plug is not a good idea?

I mostly run at about 4000 rpm or more (running to the fishing grounds or pulling a tube with kids on it), but do a lot of idling through all the ICW no wake zones and other stuff... 10 minute idle just to get into the waterway.
 
the hotter plug comes in IF and ONLY IF you have a fouling problem that is found NOT to be caused by mixture or timing being out of adjustment... If you run it and never have any issues then you don't need hotter pugs... ALSO I ALWAYS carry an extra set of gapped plugs and a wrench to change them when running a 2smoke
 
phatdaddy said:
what oil are you burning?
Click to expand...

I use the cheap oil... usually pick it up at WalMart. Sometimes the Evinrude stuff, sometimes the generic-looking stuff in the blue gallon container (don't remember the brand).

On Sunday, it ran awesome. Had it running over 40 mph on the way back in with a light east wind and a small swell behind us. That's with 4 grown men plus scuba gear. I have a 6 gallon pony tank with fresh 93 octane, so I may mix some seafoam with it and do the decarb, but everything seems in good working order.

I had replaced the throttle shift arm back in November after a failed fishing trip, but only started the engine and didn't actually run the boat after the part swap. Then started it in December and felt like something was off. Tach was racing up to 4000 rpm at idle, but I think the tach may have gone bad. Eventually I had a neighbor (not an OMC guy) come check it out with me and he thought everything was fine, but it needed new plugs and some heavy running. Seems to have done the trick.
 
Try PENNSOIL premium plus synthetic blend oil. It helped me out ALOT with idling. My big 225 that I had didn't idle for crap because of how I had ported it, but on the PENNSOIL I could idle for hours on end with it. I tried the MERC stuff once, and barely made ito ut of the idle zone at the ramp with it.
 
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