Farmall H Popping Under Load

Hi everyone. My 1949 era Farmall H magneto ignition is running rough/popping while under load, such as pulling a log or even just going up a not so steep incline. I've had this unit for 22 years and never encountered this problem. It starts right up, no problem. It idles like a purring kitten. Throttle wide open, it runs with no problem and sound normal. Under a slight load, it sputters and pops until it catches up to the load. If I rapidly advance the throttle from idle to high speed, it sputters/pops until it catches up. Runs full throttle fine. At first I thought it was starving for fuel, but now I'm starting to think it might be rich. If I pull the choke on while running wide open, it mimics the same problem as when under load.

I cleaned the bowl, replaced the in-line fuel filter, pulled the line off the carb and cleaned the screen which wasn't really dirty. I blew out the line with compressed air, as well as back into the tank. With the fuel line off and valve open, fuel flows steady from tank. I pulled all 4 plugs and they jump a spark while holding them about 3/16" away from ground. The firing order is correct 1342. The cap had some dirt and I cleaned it out, but noticed the center carbon springy thing fell out. The spring deteriorated. I put on another used, but good cap I had. Also cleaned up the rotor and cap contacts with a dremel wire wheel.

The spark plugs were carboned up. I wire brushed them and used a fine sandpaper between the electrodes and re-gapped them. Also, I pulled the 2-3-4 plug wires and started the engine with just #1 connected at an idle. Then put #2 on and took #1 off and so on for all 4 cylinders. The engine will run on one cylinder no matter which cylinder it is except #4 will run only a couple seconds before stalling. This test was done before I cleaned the plugs. Since #4 would stall, I switched the 3 & 4 plugs. I didn't get chance to see if #4 will run better by itself yet.
The high speed jet on carb is 2-3/4 turns out. Also, 3 turns out makes no difference.

I think my next step is to take the carb apart. I rebuilt the carb about 5 years ago. I've also switched to non-ethanol 89 octane fuel.
I'm open to all thoughts. And I'll be honest, that governor confuses me a little.

Thanks for reading,
Harry

Either lean or weak spark.

Sounds like you've done everything EXCEPT
clean and re-gap the points in the mag.

(quoted from post at 20:30:38 12/28/20) Sounds like you've done everything EXCEPT
clean and re-gap the points in the mag.

Click to expand...

Was thinking of this step, but could that be an issue if it starts easily and jumps a spark 3/16 of an inch? It even runs on one cylinder. I also did notice that the rotor gear has left and right play of about 1/4" on the outer most diameter.

Feel the coil once it has run for a while, if hot replace it. Good idea to set
the valves since you say # 4 won’t keep running. Ideal is to check
compression. Could be a tight valve.

(quoted from post at 21:26:39 12/28/20) Feel the coil once it has run for a while, if hot replace it. Good idea to set
the valves since you say # 4 won t keep running. Ideal is to check
compression. Could be a tight valve.

Click to expand...

Yes I was thinking of compression. Need to get me a gauge. What should compression be?
As for the valves, I'll have to look into how they are adjusted. I never did this since I've owned it.

I missed that it has a mag. Check the point gap. Coil or condenser in mag might be culprit.

CHeck for an intake manifold leak with raw propane (small tank with nozzle off the pipe) also turning the load screw that small amount is not
significant, but a start. It should just show a tiny trace of darker smoke under load. Such as up a hill in 5th. COmpression check, valve
adjustment another compression check. Best of luck. Jim

I doubt a compression issue if it starts well and idles smooth.

Lean, lean, lean, check there first, if not then weak spark.

To me that sounds like a spark plug problem. How did
the cone shaped porcelains around the center
electrodes look. If they did not clean up real good the
slightest misfire or over choke can cause them to
misfire under compression pressure. I would try a
new set of plugs.

(quoted from post at 23:27:37 12/28/20) To me that sounds like a spark plug problem. How did
the cone shaped porcelains around the center
electrodes look. If they did not clean up real good the
slightest misfire or over choke can cause them to
misfire under compression pressure. I would try a
new set of plugs.

Click to expand...

I'm gonna get some new plugs. I'm running the Champion D21s. Does anyone have a better alternative? Or best to stick with the D21? I will get new points & condenser as well.

Should check the plug wires & maybe even replace
them. Our SC had the original wires, which were
solid core, go bad. It had problems such as you
describe. New solid core wires fixed it up like new.
Jim

If you swap plugs from hole to hole, say #1 plug to #4, and the issue follows the plug, it is plugs. But two things need mention. I was told by my
Automotive Tech teacher never to use a wire brush on plug, the porcelain is then contaminated with metal from the wires and will either not operate,
or fail soon. Sand blasting works OK, but can dull the finish on the center electrode porcelain, making it foul easier. Todays lead free fuel is
less fouling. I have stopped believing in Champion Plugs. NGK, Nippondenso, Bosch equivalent are better. Your choice of D21 as a heat range is OK
when replacing them. If new plugs do not do it, do the compression test (follow directions--including open throttle, and charged battery, all plugs
out and at least 6 compression strokes. same number of strokes on each cylinder. Jim

yes , i learned that also and also to open up the tab a hair if need be , then file the electrode flat then regap and its as good as new. thats what i do . very seldom buy plugs. have vehicles with over 200k on them with original plugs untouched.

(quoted from post at 11:32:13 12/29/20) If you swap plugs from hole to hole, say #1 plug to #4, and the issue follows the plug, it is plugs. But two things need mention. I was told by my
Automotive Tech teacher never to use a wire brush on plug, the porcelain is then contaminated with metal from the wires and will either not operate,
or fail soon. Sand blasting works OK, but can dull the finish on the center electrode porcelain, making it foul easier. Todays lead free fuel is
less fouling. I have stopped believing in Champion Plugs. NGK, Nippondenso, Bosch equivalent are better. Your choice of D21 as a heat range is OK
when replacing them. If new plugs do not do it, do the compression test (follow directions--including open throttle, and charged battery, all plugs
out and at least 6 compression strokes. same number of strokes on each cylinder. Jim

Click to expand...

I may have found the culprit. Before I left for work today, I checked the wires with an ohm meter. The #4 wire was giving bad readings depending on where I probed it on the cap end. The brass end was more tarnished than the others. I went to remove the end and it broke right in half. The end of the copper wire was corroded. I found a new end in my box. I cut an inch off the wire to some bright copper and put the new brass on it. The ohm readings were solid!

I had to go to work, but I'm anxious to try it when I get home. I'll let you know.

Check them all for corrosion.

(quoted from post at 16:10:41 12/29/20) Check them all for corrosion.

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Well I got good news and I got bad news. First, I just want to thank everyone for helping me think this through.

I got home, put the plugs wires back on, with high hopes that the fix I made on the bad #4 wire was gonna fix it. I put the wires back on and she started right up. But while warming up, I could still hear that miss. Made a couple fast pulls on the throttle from idle to high speed and it still made the struggling popping sound. So I dropped it down to a lower RPM and did the one cylinder run check again as I mentioned in the OP. In my OP, I mentioned how they all would run on one cylinder except #4 would stall. When I put the plugs back in yesterday, I switched the #3 & #4 plugs. Today as I checked each cylinder one at a time, they all ran except for #3 now. So back to my spare parts box I go to get an old D21. Cleaned it up a little and gapped it and stuck it in the #3 cylinder. Started it and the miss was gone. No more struggle going from idle to high speed. Pulled the wires off again to run each cylinder one at a time and they all kept running. Took the tractor on a slight incline and no more popping. For the final test, I took it on a steep incline, put it in 4th gear and from a dead stop she pulled right up that hill without any hesitation. Put a smile on my face. So it all boiled down to one bad D21. The plug had spark, but I guess under a load it wasn't good enough.

So my next step will be to replace the plugs, wires, cap, rotor, points & condensor. It's due anyway.

Thanks again everyone,
Happy Harry

(quoted from post at 11:32:13 12/29/20) If you swap plugs from hole to hole, say #1 plug to #4, and the issue follows the plug, it is plugs. But two things need mention. I was told by my
Automotive Tech teacher never to use a wire brush on plug, the porcelain is then contaminated with metal from the wires and will either not operate,
or fail soon. Sand blasting works OK, but can dull the finish on the center electrode porcelain, making it foul easier. Todays lead free fuel is
less fouling. I have stopped believing in Champion Plugs. NGK, Nippondenso, Bosch equivalent are better. Your choice of D21 as a heat range is OK
when replacing them. If new plugs do not do it, do the compression test (follow directions--including open throttle, and charged battery, all plugs
out and at least 6 compression strokes. same number of strokes on each cylinder. Jim

Click to expand...

Thanks for that info Jim. I never heard about the wire brushing being bad for the plugs. Makes sense. My shop teacher would mention how the sandblaster would wear the porcelain though. I wanna try a different plug brand. I read some guys like the Autolite 3116. Lately, I've become a fan of NGK plugs in my cars. Not sure what number NGK would be to equate the D21 heat range.

Have you ever run the 3116? Or would you prefer the NGK? Any idea on an NGK number?

Thanks,
Harry

Running that good, would be acceptable. Replace the plugs, but leave what isn't broken alone. If the points are hitting each other off center,
or have a peak on one side and a pit on the other, those need to be replaced as well. But putting parts in it can cause more issues than a
running tractor. Use NGKs or your other option is good as well. Jim

Ngk ab 6

I worked on a generator set that had a Hercules
4 cyl. engine. The guy had 4 new Champion J-8s
to put in it. The engine would only run on 3 cyls.
no matter what I tried.
Got to checking the plug that wouldn't fire, & it
was shorted---new out of the package. Put another
plug in & the engine ran like new.

Moral of the story----never assume a new plug is
good.
Jim

So I'm going for a new wire set today from the Case dealer. I asked if they were copper core wires. He couldn't answer the question. He just said they were from Case IH. I hope they are copper core!

Copper core, or Magnetic suppression. The Manetic wires are metal conductor, with spiral wound wires that wrap a kevlar core. They are as conductive
as solid, but do not make radio static. A complete set for a V8 or 6 cyl might be cheaper than the caseIH set, and that set might be carbon resistor
wires. Jim

I also notice my cap terminals look to be brass? Or could it be copper? I have another cap that looks to be aluminum. One would think brass to be better than aluminum, but actually aluminum is more conductive than brass. At least that's what I found on the internet.
Harry

Except that the difference (though substantial) is irrelevant when dealing with 10,000 volts. SO the real difference is the corrosion tendency
of either, and brass is far less likely to turn to powder. Use the brass one. Jim

So I picked up a set of wires from the Case IH dealer. They are in fact copper core. But the flat brass ends that need to be attached to the wire actually have a hole in the center about the diameter of the copper wire itself. This is the end that goes into the cap. My old wire ends are similar but they had a wedge spike that stabbed right into the copper core wire. I'm a bit confused with these ends with the holes. Am I supposed to strip the wire back a little and stick the copper core through that hole? To top it off, the wires, cap & rotor are made in China. I'm tempted to take them back and buy the parts from Steiner since their wires & cap say made in USA.

I've never seen these ends with holes in them before.
Harry

The wire is twisted and poked through, I like to flatten them out like a starfish, so they drape back toward the insulatein. If they take solder
well, making the "star" just the size of the circular end, then soldering them on with rosin core solder makes a nice finish. Jim

(quoted from post at 21:58:29 12/30/20) The wire is twisted and poked through, I like to flatten them out like a starfish, so they drape back toward the insulatein. If they take solder
well, making the "star" just the size of the circular end, then soldering them on with rosin core solder makes a nice finish. Jim

Click to expand...

Ok. So are you making the star under the end cap or poking through the hole and then bending it back over the outside of the cap?

After poking it through. More like Boris Johnson's hair cut than a "Star" (UK prime minister) Jim

(quoted from post at 13:46:29 12/31/20) After poking it through. More like Boris Johnson's hair cut than a "Star" (UK prime minister) Jim

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Ha!!!