which spark plugs for my H?

c1802362 · Oct 22, 2009

I pulled the plugs on my '41 H as the engine has been puffing smoke recently. I've got wet oil on two of the plugs and a rich mixture on the other two. So, after I check the timing, the next thing is to put the correct heat plugs in.

The question: what type plugs would the the best in this situation? The IH parts catalog gives P/Ns for normal, light, severe, and extremely severe service. I won't be in a position to tear into the head or engine until winter and I have the fall hayride season coming up in a few weeks.....

Art

Brian Schmidt · Oct 22, 2009

I prefer AutoLite plugs. 3116 I have found work the best in these if you are not working it hard. If you do work it hard, I find that 386 are best.

rustred · Oct 22, 2009

you want plugs for light use, which would be a hotter plug than normal. just starting and stopping the engine never reaches its operating temp.you will see the plugs getting oil fouled. should take it out every so often and give it a workout for a few hrs.adjust your carb. also. just reading the plugs can tell a lot about the engine.

mhmalcolm · Oct 22, 2009

I agree with Brian. Autolite 3116 plugs if you have a worn engine and are burning a little oil, or for light duty (parade) use.

John T · Oct 23, 2009

If the tractor is used hard so the temp gets and stays up plug fouling isnt so bad butttttttt light duty parade use and puttering around can lead to premature fouling. It can help if you use thermostat or air restriction to get n keep the temp up to 180 or more,,,,,,,,,,,dont run the carb any richer then necessary,,,,,,,,,use hotter plugs,,,,,,,,,have the ignition well tuned and use wire core versus carbon core suppressor plug wires.

Autolite 388 is hotter then 386 but the 3116 is a non resistor plug in the same heat range. Id opt for the 3116 if you prefer a non resistor plug but 388 otherwise. One old mechanic/farmer story is to use an extra plug washer to make the plug run a bit hotter. Of course Ive never did any scientific test to determine how, if any, effective that is, but if the plug seal is still good seems to me the plug would be a bit hotter whch may help burn off potential fouling deposits like oil or unburned fuel (carbon build up)....

John T

Dellbertt · Oct 23, 2009

I have been using AC87 for over 15 years in all older gas Farmall, JD etc tractors with no problems.
Dell

c1802362 · Oct 23, 2009

thanks - I'll take your advice - Art

soybeanjoe · Oct 23, 2009

I use to run Champios in my SMs & SMTA but was always having trouble fouling plugs. On the advice of several people I switched to the Autolite 386s but still had some fouling problems, but not as bad as with the Champions. Heaviest work the tractors get is auger duty.

The local auto parts store counterman called Autolite & they recomended 3116s with todays gasoline in the IH 4 cylinder engines & to use 386s in the 6 cylinder engines. Since switching to 3116s I seldom have a plug foul. FWIW

which spark plugs for my H?

c1802362

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Brian Schmidt

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rustred

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mhmalcolm

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John T

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Dellbertt

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c1802362

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soybeanjoe

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