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powermax_paul

Spark Plugs

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powermax_paul
I've been using Champion H10C's in my Onans just because they're easier to find than the H8's that are recommended. Regardless, I keep fouling plugs. Is there a better plug to use to replace the H-8? I can't find an NGK equivalent in any charts. Paul

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Floydster
Paul The NGK plug no. B-6L is the cross reference to the Champion H-10C. I am still running H10C plugs in both of my 620's, I put a couple ounces of Sea Foam in each tank when I fill up. I haven't fouled a plug in the last five years Iv'e been doing this, before that I was fouling these champion plugs regularly. The reason I haven't changed over to the NGK's is because I had a case of twenty five I purchased at an auction. They are just about gone. Hope this helps, Floyd

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argz
I hope I'm not opening a big can of worms here, but... my experiences with plug fouling have been carburetor tuning related. Usually it is when the mixture is too rich on the top end, that is the high speed mixture. I will admit that my plug fouling experience is from motorcycles, not necessarily tractors, but I would think the theorys are the same. If it fouls the plug at idle, then you have too much fuel at idle, if it fouls it at speed, then the high speed mixture is too rich. If it's oil fouled, then you have bigger problems, either oil is leaking past the valves or the piston rings are worn. That can be tested with a compression check. Regardless, try leaning out your mixture first. -Rich

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BradW
Whatever you do don't run ngk plugs, they will crap out on you, they never last in my 3 wheeler or anything else I have tried them in, stick with champion, they work the best in my opinion, that was stock plug,-BradW

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powermax_paul
Actually, I've been running all three of my onan's pretty lean. I may be burning a little oil, but I'm not smoking on any of them. The 4041 has less than 50 hours on the rebuild. My newer 9020 has always fouled plugs since I got it 12 years ago with 450 hours. All three tractors foul plugs and everything is set to specs. Paul

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gretsch
I had the same problem with a cast iron briggs 16. Tried everything I could think of or was advised to do. Changed out complete ignition setup, converted from points to magna-arc, boiled out and rebuilt carb twice, cleaned heads and intake chamber, ect....Finally and old Ariens mechanic told me it was possible the oil rings were weak, changed out rings and no more fouling. I never suspected rings because the compression was perfect, the motor never smoked (except when the plug started fouling), and very low hours on an old engine that was clean as a whistle on the inside. But it fixed the problem. Has no more power or compression than before, but does not foul plugs. I use Champions in it because of ease of availability, however my truck and car plugs are NGK. They will go 100,000 miles and still look new with neglible electrode wear (they are platinum however). Recently I tried an Autolite platinum plug that was on the clearance rack at Walmart, it looked very similar to the J19Lm's, worked and fit perfectly. I'll see how it's doing in a couple of years.

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JonetteP
Hi paul, we have had the best experience with NGK plugs. What we have heard from "plug people" is that NGK uses better grades of insulators. We use there plugs in everything from chainsaws, to our 4040, and 9020 units. On average the plugs seem to start better for our customers. We also have less of a problem with fowling. We were a polaris dealer for over 35 years. We have had less problem with NGK than other plugs. They are very consistent in our experience. Hope this helps.

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