41 Model H inconsistent starting by hand

areeves

New User
Location
Colorado
Hi, all.

I’m a relatively new member of the forum and essentially a novice 2-cylinder mechanic.

I have a 1941 Model H hand start tractor that was largely restored when I bought it. I’ve done a little work to get it running, and it runs well: it sounds and seems to act pretty good when running, as far as I can tell.

Starting the tractor, though, is a little inconsistent. A few times, it’s started very easily when I turn the flywheel. Other times, I can spin the flywheel for ages and not get anything. I’ve noticed that on the first spin after sitting for a few hours or overnight, it really sounds like it wants to run, and sometimes will. If I can’t get it started on the first spin or two, though, that’s usually a sign that I’m not going to have much luck starting by hand. I can pull start it pretty consistently.

I can imagine several possible causes: too much choke, not enough choke, too much fuel, not enough fuel… maybe a weak spark?

Rather than trial, error, and guesswork, can anyone suggest a systematic way to troubleshoot the problem? Any other thoughts or pointers?

I also have a ‘41 Model A that I can start by hand very consistently, but I may not yet know the quirks and personality of the H.

Thanks!
 
Hi, all.

I’m a relatively new member of the forum and essentially a novice 2-cylinder mechanic.

I have a 1941 Model H hand start tractor that was largely restored when I bought it. I’ve done a little work to get it running, and it runs well: it sounds and seems to act pretty good when running, as far as I can tell.

Starting the tractor, though, is a little inconsistent. A few times, it’s started very easily when I turn the flywheel. Other times, I can spin the flywheel for ages and not get anything. I’ve noticed that on the first spin after sitting for a few hours or overnight, it really sounds like it wants to run, and sometimes will. If I can’t get it started on the first spin or two, though, that’s usually a sign that I’m not going to have much luck starting by hand. I can pull start it pretty consistently.

I can imagine several possible causes: too much choke, not enough choke, too much fuel, not enough fuel… maybe a weak spark?

Rather than trial, error, and guesswork, can anyone suggest a systematic way to troubleshoot the problem? Any other thoughts or pointers?

I also have a ‘41 Model A that I can start by hand very consistently, but I may not yet know the quirks and personality of the H.

Thanks!
I have an H that acted like that, turned out it had a crack near the center stud leaking just enough coolant to dampen one of the spark plugs. Got it stitched and starts beautifully now.
 
Hi, all.

I’m a relatively new member of the forum and essentially a novice 2-cylinder mechanic.

I have a 1941 Model H hand start tractor that was largely restored when I bought it. I’ve done a little work to get it running, and it runs well: it sounds and seems to act pretty good when running, as far as I can tell.

Starting the tractor, though, is a little inconsistent. A few times, it’s started very easily when I turn the flywheel. Other times, I can spin the flywheel for ages and not get anything. I’ve noticed that on the first spin after sitting for a few hours or overnight, it really sounds like it wants to run, and sometimes will. If I can’t get it started on the first spin or two, though, that’s usually a sign that I’m not going to have much luck starting by hand. I can pull start it pretty consistently.

I can imagine several possible causes: too much choke, not enough choke, too much fuel, not enough fuel… maybe a weak spark?

Rather than trial, error, and guesswork, can anyone suggest a systematic way to troubleshoot the problem? Any other thoughts or pointers?

I also have a ‘41 Model A that I can start by hand very consistently, but I may not yet know the quirks and personality of the H.

Thanks!
I have a 1940 H and behaves exactly like you described.
If it doesn't go on the first crank- it's going to be a rough half-hour of fiddling with it. (choke, throttle, etc.) It's frustrating and I often avoid using the tractor because it could be such a pain to start.

My magneto is re-built and the spark plugs are 'new'.
I'm watching this thread for suggestion replies.
 
Although the early Owner’s Manuals state that a magneto should be able to make a spark to jump a 1/8” gap, the later SM-2029 (John Deere Electrical Systems Service Manual) says that a magneto must be able to make a spark jump a 9 mm gap (0.35”, which is between 5/16” and 3/8”) consistently without a misfire. A hotter spark will definitely improve starting. Spark plugs need to be reasonably clean and gapped correctly (0.30") .Another crucial item is the carburetor – worn throttle shaft bushings and/or worn throttle plates will affect the air-fuel mixture and will cause harder starting as well as poor running behavior. Use fresh fuel – fuel that is several months old and that has been heated up from being baked by engine heat will loose some volatility. It seems that most “H” tractors start best with the throttle almost completely closed and with little or no choking unless the weather is quite cold. And most “H” tractors are easily flooded by choking too much. However, every tractor behaves differently. Incidentally, low compression doesn’t necessarily cause poor starting – think about how compression release petcocks work…
 
Try setting your throttle in different spots till you get a response. My 39 wouldn't start if it wasn't in the correct spot.
 
Thanks, everyone, for the helpful replies so far. It will take a little while for me to work through these, but I’m eager to get started. In the meantime, I have a few follow-up questions and responses:

1) What is the best way to test the spark on a hand-cranked tractor like this one? Is there a suitable spark tester?

2) If the spark is good, that suggests to me that everything upstream to the magneto should be ok as well. Is this right?

3) If timing were an issue, I’d expect to hear something amiss while the tractor is running as well, not just at startup. Is this correct? When running, it sounds pretty good to me. I’ve attached a short video so others can hear it as well. More experienced operators may detect something that I’m missing.

4) Based on comments here, I may be over choking and flooding. Daytime temps here are currently in the 40’s, so not too cold yet. I follow the same procedure to start my A, but it may be more forgiving than the H.

Thanks!


 
Hold the wire that you take off of one plug about 1/4 inch from the block. Turn it over slow & when the impulse trips you should see a nice blueish white spark.
 
Thanks, everyone, for the helpful replies so far. It will take a little while for me to work through these, but I’m eager to get started. In the meantime, I have a few follow-up questions and responses:

1) What is the best way to test the spark on a hand-cranked tractor like this one? Is there a suitable spark tester?

2) If the spark is good, that suggests to me that everything upstream to the magneto should be ok as well. Is this right?

3) If timing were an issue, I’d expect to hear something amiss while the tractor is running as well, not just at startup. Is this correct? When running, it sounds pretty good to me. I’ve attached a short video so others can hear it as well. More experienced operators may detect something that I’m missing.

4) Based on comments here, I may be over choking and flooding. Daytime temps here are currently in the 40’s, so not too cold yet. I follow the same procedure to start my A, but it may be more forgiving than the H.

Thanks!


View attachment 98640

As teddy52food mentioned, you certainly could hold the spark plug wire 1/4" away from the block and then rotate the flywheel, but it's not easy to hold the plug wire steady and rotate the flywheel at the same time - by yourself. I made a very simple "tester" that lets me connect a plug wire to one side while a ground wire is attached to the other side. The two copper leads can be bent to the desired gap. In this case, the leads are 9mm apart, and my magneto will easily jump that gap with a nice blue spark while slowly rotating the flywheel. This "device" works very nicely, prevents the possibility of receiving a nasty electrical shock while holding the plug wire, and is easily adjustable. As a quick test, one can simply rest a spark plug against the top of the block or comparable surface while making sure the plug wire terminal is away from that surface. However, because the gap of a spark plug is so small, any spark seen there doesn't give one a good idea of the strength of the magneto.

Incidentally, be VERY careful with such testing. There have been some very bad accidents resulting from rotating a flooded engine with the spark plugs removed - raw gasoline can be expelled through the open spark plug hole and if the magneto creates a spark, a nasty explosive fire can result - not a good situation if your pants were sprayed with gasoline....

Regarding timing, if it is too advanced, you will know because your engine will kick backwards because it fires too early. If it is too retarded, the engine might seem somewhat sluggish to start, but it will still fire. Assuming that everything mechanical is timed properly (flywheel to crankshaft, camshaft to crankshaft, lag angle set properly in the magneto, etc.), the impulse of the magneto should "snap" just when the "LH IMPULSE" letters on the flywheel are exactly at, or very slightly beyond, the 3 o'clock position when rotating the flywheel (and again 180 degrees of flywheel rotation later). At the same time, the slots in the flywheel should be horizontal.

spark tester.png
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top