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Best plug for H

R

ryanwheelock

Member
I know this topic has been debated before, which spark plug is best in Farmall H.
My question is what would you recommend for an H that has some oil blow-by from the rings would be the best plug. Its always had Champion D16's in it. Would it be better to run a hotter plug with the bit of oil blow-by??? Only use this tractor to move a few hay wagons during the summer. Seemed like last year it oil fouled the plugs once or twice under load. Would like to run it this summer and rebuild the engine next winter. With Champion plugs the higher the # the hotter the plug??
Anyone ever heard of a thing that screws over the end of the plug to prevent it from foulng?? Parts store has them but I'm sure it wont cure my problem like a rebuild.
Ryan
 
Champion D 21's or Autolite 386's are a hotter plug. The D 16's are on the colder end of the heat range. During the summer run a heavier oil such as a straight 40 or 20w-50. The plug extenders you talk about are designed so the plugs elextrode do not go as far into the combustion chamber as normal. This means there is less chance of them being covered in oil. These help some also, worth a shot they are cheap. This will help some till you get a rebuild in there.

Andrew
 
Ryan - A hotter plug will definitely help reduce the oil fouling.

For Champion, higher numbers = a hotter plug. For an H my recommendation is use a D21 - or even a D23 if you can find 'em.

Note that even after a rebuild and your engine no longer burns oil, unless you work the tractor HARD you will have best luck with the D21 or the Autolite heat range equivalent (386 or 3116?).

Reason: The lousy gas we get now seems to have a propensity to foul plugs in lightly loaded, carburetor-equipped engines.

---

I wouldn't bother with those "fires in oil" plug adapters that fit between the wire and the plug terminal. They may solve the problem for the moment. But you'll find the plugs will still foul and misfire after another hour or two of running. They also seem make the rest of the ignition system more prone to shorting/misfiring problems, especially under wet conditions.
 
I'm pretty darned sure that all Hs had the sawtooth throttle from the factory.

Anything else would have been aftermarket.

Allan
 
My 1948 has a friction type and I think 90% of H's had the friction type. Think only the 1939 40 and 41? 42? had saw tooth, just wondering when they changed em. Just like the pto's on early models.
 
If it has a magneto, Autolite 3116's

If it is battery ignition, Autolite 386's, or if you want a hotter plug, 387's
 
Correct. The Hs and Ms ALL used the sawtooth throttle right up through the Supers and even the SMTA in 1954. The friction throttle is an aftermarket item from M&W but is still available through the aftermarket.
 
It has been replaced at some point.

Darnit! That's the trouble with being so old that you can remember 'em when they were new. :>(

Allan
 
It has been replaced at some point.

Darnit! That's the trouble with being so old that you can remember 'em when they were new. :>(

Allan
 
Yep,

I don't know which company did it, but they copied the John Deere's 50,60 and 70 which had that "new fangled" friction throttle contraption. :>)

Allan
 
Most if not all Hs had saw tooth when new (our 1947 had saw tooth whem new). IH came out later with similar replacement throttle that had square notches with replaceable tooth on lever, all of the friction throttles are non IH M$W made them first and now there are Chinese knock offs. You will not find friction throtte in IH parts book.
 
The correct spark plug for your engine is the one that will give good life without fouling and yet run cool enough to avoid preignition. On some worn engines you may need to run plugs of different heat ranges in one or more cylinders.

The original spark plug recommendation was a Champion D16 for general use. That was changed (50's - 60"s?) to a D15Y which is one heat range colder but with an extended tip to get the spark further into the combustion chamber. With the end of leaded gasolines the recommended plug was changed to D18Y for general use. A D15Y is still recommended for use with heavy loads. A D21 can be used for light loads. If you use a D21 under heavy use you will get preignition caused by an overheated spark plug igniting the fuel load before the spark occurs.

If when you shut off the tractor and it wants to keep running by dieseling it is a good indication of too hot a spark plug. Engines that are burning some oil can use the hotter plug because the buildup of carbon on the electrode has an insulating effect and makes the plug act as a colder style. Carbon buildup can also become hot enough to burn under heavy load and that can in turn lead to a preignition or dieseling condition.
 
autolite 3116 is what you need. My working H burns a little oil, went through many 386's. Put ion a set of 3116's about a year and 1/2 ago, have not even had to clean them yet.
 
I switched from Champions to Autolite 386s in my letter sries tractors a few years ago because of excessive fouling. The tractors still had some fouling issues with the 386s, though nothing like with the Champions ao I had the local auto parts store call Autolite to get thier recomendation on the correct plug to use. According to the Autolite tech 3116s are the appropriate plug for the older IH 4cylinder engines used in the letter series & 300-450s with today's gasoline aHe also said that the 386 plugs are for the 6 cylinder engines used in the 4/560s & later.

Since switching from the 386s to the 3116s plug fouling has become almost nonexistent
 
(quoted from post at 13:19:09 02/11/10) Correct. The Hs and Ms ALL used the sawtooth throttle right up through the Supers and even the SMTA in 1954. The friction throttle is an aftermarket item from M&W but is still available through the aftermarket.
Click to expand...
Well, not exactly. When the Supers - at least about the time the stage 2 supers came out - they came with a different version of the sawtooth throttle which had "square" teeth instead of "saw" teeth. Easy to spot from a distance by the "rivet head" on top of the bell. My stage 2 SH and SM both have the square tooth versions. mike
 
My opinion is that the square toothed ones are replacements, they came out after the SM/SMTA, etc were no longer in production. My dad's H got the replacement in the late 50's. The square toothed one is not in my Super H parts book, and it had the saw toothed one on it when I bought it.
 
I have one of the last H's made and it has the saw tooth. I always though the friction type was M&W.
 
My late 53 Super M has the square tooth throttle. I know it has had it since it was new to. My dad always used to comment that he thought the square tooth was hard to get used to when grandpa bought the tractor new compared to the H's and M with sawtooth throttles they had before. Dad always felt the square tooth didn't have the fine rpm adjustment the older sawtooths did.
 
(quoted from post at 03:46:21 02/12/10) My opinion is that the square toothed ones are replacements, they came out after the SM/SMTA, etc were no longer in production. My dad's H got the replacement in the late 50's. The square toothed one is not in my Super H parts book, and it had the saw toothed one on it when I bought it.
Click to expand...

Yes, I think the square toothed throttle was a replacement for the worn out saw tooth, but was never factory installed. My 1940 M has the square toothed throttle.
 
CNKS, no it didn't make it in the parts book, but IH sent out a bulliten to the parts system that the governor control 51348 DAX was being replaced by 361244R11. New sector has square notches compared to present part with saw tooth type notches. Effective at serial # 26561 SH and 71718 SMTA. Both made in May 1954. States that new design complete will interchange with the previous type. Square tooth was also sold under part # 366727R91 and maybe others in IH parts merchandising catologs. Later type was used as replacements after saw tooth type run out and its probably a rare tractor that never had those parts replaced more than once.
 
(quoted from post at 11:45:58 02/12/10) CNKS, no it didn't make it in the parts book, but IH sent out a bulliten to the parts system that the governor control 51348 DAX was being replaced by 361244R11. New sector has square notches compared to present part with saw tooth type notches. Effective at serial # 26561 SH and 71718 SMTA. Both made in May 1954. States that new design complete will interchange with the previous type. Square tooth was also sold under part # 366727R91 and maybe others in IH parts merchandising catologs. Later type was used as replacements after saw tooth type run out and its probably a rare tractor that never had those parts replaced more than once.
Click to expand...
hanks, Dave. mike
 
That explains why my Super H that my dad bought new in early 1954 (sn 17556) had the saw tooth throttle and he later converted to the square tooth throttle which it has today. Roger
 
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