Spark plugs for Farmall H

I know this has been discussed before, however I can't seem to find it in archives.
All the IH parts cataloges and shop manuals make recommendations for plug make and size. However they were assuming at that time that we would be burning distillate or kerosine, not the modern etanol-laced gasoline.
What plugs do Ya'll recommend for a recently restored Farmall H, C-152 engine, 6 volt w/ distributer?

I have the autolite 386, no issues.

The Autolite 386 or slightly hotter 388 will work just fine, although the Autolite 3116 is a non-resistor type and might be even better. I've used both in my Hs and got along quite well with either one.

Currently using the 3116s in a 1940 Farmall H that is running on straight E85. NO problems.

Best I can tell the Autolite 386 was close to factory original heat range while 388 is a tad hotter, maybe better if compression is gettin low and she using a little oil or youre using it for light jobs or parades etc. A battery powered coil distributor ignition can tolerate resistor plugs better then a magneto where I prefer 3116 which I believe is a NON resistor plug. However the NON Resistor 3116 would also be okay regardless if distributor or mag so Id try 3116 or 388. A good tune up and good wires also helps regardless what brand plugs you run.

John T

John T: I have timed and replaced points & wires.
So I gather you are recommending AUTOLITE 3116?
What is resistor/ non resistor all about?

(quoted from post at 08:31:50 08/06/12) John T: I have timed and replaced points & wires.
So I gather you are recommending AUTOLITE 3116?
What is resistor/ non resistor all about?

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The industry developed the resistor type plugs sometime back in the 50s (I think) to suppress the static given off by the ignition system which interfered with TV, AM radio, and other communication devices.

It basically takes a little stronger spark to get the same results with a resistor type plug than would be needed with a non-resistor plug, which means the non-resistor plug SHOULD give better performance.

I've only just brushed the surface with my explanation. It gets a LOT deeper if you want to dig. JohnT can explain it better.

Like Rusty noted resistive suppressor (some are carbon core instead of wire) wires n plugs came into the picture (among some other reasons) partly to reduce RFI noise to keep the radio quieter. The thing is the coils HV secondary output of a relatively low energy Magneto matches up much better if theres little resistance/impedance in the plugs and plug wire circuit (NOT counting for the open gap), so regular non resistor plugs (what was used when mags were developed) are preferred. While that issue is less relevant in a batetry powered coil distrubutor ignition I figure one may as well use a non resistor (3116) plug there also. While its not much, Id just as soon discharge all the avaialble stored energy the coil has to offer by discharging it across the plugs gap (volts x amps x time) versus as I squared R heat loss in resistor wire or resistor plugs. This is similar to my preference of bigger then stock battery cables on 6 volt tractors, say 0 or 00 versus No 1 or 2, Id again (regardless if not all that much difference) just as soon discharge it in the starter then I squared R heat loss and voltage drop in the cables, since when its extremely cold, the starter may draw twice the normal current (say 300 amps instead of 150), battery voltage may drop to 4.5 instead of 6.3, and ALSO battery efficiencty is greatly reduced at cold temps.

But Hey Im just wired that way and am conservative and yes I MIGHT over build and over design now n then, its just how I was raised n trained. I doubt the performance would be much (if any) different if you used 386 instead of 3116 and unless its extremelyyyyyyyyy cold your old girl would probaly still start heck even if you used 4 gauge cables lol

BUT THATS MY STORY N BY GOLLY IMA STICKIN TO IT

John T A CONSERVATIVE what can I say

NAH, I wouldnt say I can explain it any better, but I betcha I can use more words doing it lol lol thats just the engineer and lawyer in me I CANT HELP MYSELF!!!!!!!!!!!!!!!

As always, fun chatitn at ya

John T

Engineer AND Lawyer? What a diametrically opposed combination!! My RN sister married an Engineer and I thought that was bad, but to be BOTH a Lawer and Engineer must make it hard to decide which side of the bed to get out of in the morning! LOL!!

Anyhow... if I get Autolite 388 or 3116 whatdo I gap them at?

(quoted from post at 10:37:02 08/06/12) Engineer AND Lawyer? What a diametrically opposed combination!! My RN sister married an Engineer and I thought that was bad, but to be BOTH a Lawer and Engineer must make it hard to decide which side of the bed to get out of in the morning! LOL!!

Anyhow... if I get Autolite 388 or 3116 whatdo I gap them at?

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0.025"

Geeeeeeee I dont know everything lol I'm a JD man instead of an IHC but my best guess is 0.025 to 0.030 Im sure it will run anywhere in that gap range......

YOURE RIGHT anytime I have to make a decision I have to weigh all the pros n cons and look at it from BOTH sides and put it on a scale, drives the first wife bonkers lol In law school that was referred to as "thinking like a lawyer" and YES being an engineer makes it worse lol

John T

the sparkplug of of the time was champion D16 in all of these old mccormick's, i have a pile of these old tractors and damm near every one has that brand and no. in them when i bought them. everyone is braging about prestolite or auto lite being so much better but i still have not seen the advantage.

The quality of Champion plugs has slipped over the years.

Never had a problem myself but I have heard from several people getting bad Champions right out of the box. Autolites have been getting a better reputation lately.

Autolite 3116 and nothing else! My Papaw said gap them with a thin dime.