H will not start

Dave41A

Member
My new-to-me '41 H will not start. I bought it this past summer and drove it home. It would not idle, which I traced down to a bad manifold gasket and faulty idle air adjustment. Upon fixing that and cleaning lots of oily grime off the side of the engine (leaky valve cover) I noticed the head gasket was leaking from the manifold side. I pulled the head & installed a new head gasket. I would like to think I did a careful job--I chased all the threads w/ tap & die, and very meticulous numbering all parts & replacing to their exact location, etc. It holds water well with no sign of leakage into the engine.

It came with Autolite 388's and suppression wires, but I installed new Autolite 3116's, and new copper plug wires because I also installed a magneto. The magneto on it throws good 1/4 inch long blue sparks when bench tested and spun by hand. I have verified the timing--it "clicks" just past the 1st of the timing marks with the magneto. I have bright blue sparks at the plugs when tested outside the engine.

After no luck with that I reinstalled the distributor. It also sparks bright and blue.

I could get the tractor to cough a little once with the magneto installed and the tractor on full choke, jumping directly to the starter with a 12V battery to spin it fast. I have had no luck since then--all I am doing now is killing batteries and wasting time. The tractor has step-head pistons in it (3 7/16 bore) but is otherwise stock. I have tried spraying starting fluid in the cylinders and in the carb--no luck either way. I have even tried reversing plug wires (2-3, 1-4) in the off chance it is 180 degrees out of time. Nothing. Compression is very good, as is vacuum. On choke, it pulls a lot of fuel which comes spilling back out of the carb as soon as I stop cranking. However, the plugs do not seem wet, which is odd. Even so, I think it should cough with the starting fluid.

I'll add that it is about 16F here, which makes standing around staring at a non-running tractor all the less fun. Single digits are forecast for next week. Groundhog got it wrong this year.

I'll happily provide any additional details if requested. Any insight on what to check or try next would be appreciated. Sorry to have gone on so long, but I am completely stumped.

Thanks in advance for any suggestions. Dave41A.
 
On my handstart 39 H I have to have the throttle all the way back and just bump it forward a whisker or you can crank it til the cows come home and you won't get a pop. Mine also likes the choke, yours may be different
 
Does the magnito click when you try to start it? This is the impulse mechanism which is necessary when starting. Have a BN that would only start with throttle at idle. Cured this with governor rebuild.
Do you get any pop or poof out of the exhaust when trying to start?
Is the oil level over full?
Do you have a good hard suction at the carb input and a good strong output at the muffler?
Let us know.
Good luck.
Dave.
 
Yes, the magneto clicks when I turn it over TDC. I bought it used and did a by-the-manual rebuild (this is my 2nd. I did the same on my "A" and that one is fine). It has a new coil and throws a hot spark just turning it with my fingers on the bench.

I cannot reach the carb input with my hand when cranking (I'm jumping from the tractor's right side), but it sure draws a lot of gas up when I am cranking it. This all comes spilling back out onto the floor when I stop cranking (I have the air tube off). I can see puffs of what is likely fuel vapor from the muffler at the same time.

I'll see if I can get someone to help me crank it while I hold my hand over the carb intake & manifold exhaust.

That it won't even fire when I spray starting fluid in the spark plug hole is what has me stumped.

Thanks for the suggestion on the oil. I'll check the oil level. How would that affect things?
 
so in short you are saying it was running then you changed the head gasket now it wont start??? is that correct? and you did not touch timing? makes no sense. reread this and you installed a magneto ? ok so it is not timed correctly then.
 
Sometimes Fuel creates a film of conduction on plugs (even brand new) that shorts them when cold and will not fire. Heating each with a propane torch seems to burn this off. putting them in warm will help.
Make sure #1 is on compression then watch its (removed) spark plug to see when it fires. (#1 is at the radiator) which is not what appears on the firing order lettering on the block) rotor rotation is CW. Just as it fires #1 plug, look at the position of the piston. the next stroke should be valves closed suction on the spark plug hole (thumb in it). if not, something is wrong. Usual location for wires in the cap are #1 plug at 1:30, #3 plug at 4:30, #4 plug at 7:30, and #2 at 10:30. Jim
 
Thanks for the response. I have set the mag to "click" when I reach the 1st timing mark on the pulley. I have adjusted it a little back and forth from this point--no luck. I tried swapping wires in case I was 180 off-time. No luck.

I followed the procedure on page 44 of the IHC magneto manual. I'm timing to the "first notch" on the pulley. I assume this is the lower one as you look at it from the left side of the tractor. I am obviously missing something.
 
Thanks. No question the plugs are cold as temps are in the teens. I'll try your propane torch trick and also verify the timing of the spark using your thumb trick.
 
The first mark may be the advance mark (there are differences between years. Some marks are also to align the flywheel to grease the pilot bearing. Be sure the piston is at TDC on compression!!! (use a soda straw down the spark plug hole) Jim
 
for information for me. did you install mag, in this manner? this one on a cub. may be different. https://www.youtube.com/watch?v=QqucExhxXdE
 
Yes, very close to what I did. The H4 mag is a little different, but the principle is the same. I followed the directions on page 44 of the IH magneto manual. (GSS 5035)
 
if you have it on the compression stroke and crank it slowly very slowly so it clicks and jim's straw is at tdc it will start! get someone to run the hand crank slowly, you hold the straw and this is the best procedure , as you can see for your self where the mag click happens. THEN, fine tune with timing marks. timed many tractors like this without even looking for marks. mag's are tricky because of the impulse coupling.
 
I don't know anything about magnetos, but my H did the same thing and the center electrode of the distributor cap was worn down too much. Replaced old cap with new cap and new rotor, all fixed, fired right up.
 
I would first check valve lash for clearance. A bit loose for now is better than tight. You can adjust them after you get it running. Thenwith tappet cover off you can easily check for TDC both front next to radiator valves will be loose at rocker arms. Now check your marks on the pulley/flywheel. Might be a very small bit off so you can set it at the TDC mark now. Then check your mag or distributor. Which ever one you want on it. It should be so rotor cap is pointing to the number one plugwire on the dist cap. With gas on it should be close enough to start then you can clean things up for correct. Valve clearance,timing and tappet cover. If you want to just set the tappet cover on to keep oil from spattering around fine, you will need to keep it open to finish adjusting valves after it is hot.
 
Sorry I don?t know your degree of experience with engine repair, but I agree with Cat guy. The valve lash needs reset. The new head gasket may be thinner and now the valve lash is zero or less holding the valves open. My 2 cents.
 
Use another tractor with a belt pulley. Put them face-to-face. Put a flat belt on both tractor's pullies with a twist and tighten. Put your H pulley in gear.
Start the pulley on the other tractor. This will turn the engine of your H at a moderate speed in the correct direction and not weaken your battery.
Adjust your H as suggested until it begins running.
 
Thanks. Valve lash is a good point that I had not considered. However, I have verified that both valves close by taking the valve cover off. But I will take your suggestion and double-check.
 
Thanks. I verified the position of the timing marks when I had the head off. They are pretty much right on.
 
Drained all the old gas, replaced with new. Started right up on magneto (but had to crank it with 12V). Thanks to all for their thoughtful suggestions and input. I am not out of the woods yet with this tractor, so will be back with more questions soon.

Thanks again,
Dave41A
 
Thanks for letting us know what the solution was. It helps everyone to broaden their problem solving skills. Jim
 
see, and I was under the impression that you had the valves set. you did not say u did not set the valves. if not set then it is very possible they could have been tight and no getting enough compression to start. just because the valves are closed don't mean the valve lash is set. have you did a rough check on the lash by lifting the rocker up and down while the cyl is at tdc? if there is no clearance they are too tight.
 
Thanks. The rocker arms are loose when the valves are closed. But, I will re-check after the engine has been warmed and re-torqued, as they are probably out of spec by now.
 
It seems like you are describing an engine ready to run. Spark and fuel working as they should. That and the fact that you didn't get anything with starting fluid directly through the spark plug holes seems to point to timing. At this point I would want to confirm, by pulling the #1 plug and having a friend hand crank the engine, that you are really at the top of the #1 compression stroke as the ignition rotor lines up with #1. It's easy to detect the compression stroke versus the exhaust stroke as air will rush out of the spark plug hole on the compression stroke, at the top of this stroke you want the rotor lining up with the number one spark plug wire.
 

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