39 H

I?ve got a 39 H that always requires a little starting fluid in the piston chamber to start. Once running I have to leave the choke open part way to smooth it out the best I can. Any ideas on how to correct these problems?

I have had a few H's over the years that started hard and needed choke on part way to run right. First doing the usual carb. clean up and tune up they ended up having leaking intake manifold gaskets where it sets on the head. Don't know why only the H's had this issue ? I Never had any B's or A's do it.
Should be able to test by spraying something flammable ( keep fire extinguisher handy ) around the manifold as it runs and see if the engine changes. IIRC some use an unlit propane torch too.

My 42 does not have that problem. When you get it straightened out, make sure you can shut the gas off and let it run till it quits. Gas will go bad in the carb and gum it up.
I always run till the carb is dry on mine after using the tractor.
Just for the heck of it, run some good carb cleaner or Seafoam through the tank for a while. Won't cost much.
Richard

I always shut off the gas on my 1935 JD-B and once it dies I also open the drain cock on the bottom of the carb and drain what gas is left in it and I leave it open so water cannot condense in the carb and then freeze and break the carb. Learn the hard way that water can cause major carb damage due to freezing and finding a carb for a 1935 B is not easy or cheap

Seems I remember "Clooney" saying that he even had trouble getting a 39 H to run right. For that reason I do not even consider having a 39 H. Just say'n.

Nothing special about a 39H that would make it run or not run compared to any of the other years made ?

My 39 H starts easily and runs great.
No differences in years as far as running goes.
Probably needs carb work.

I'd look at the spark intensity at impulse (mag clicking) speed. It should give you a good blue spark at very least 1/4" long. If it won't do that, service the mag.

Second thing is spark REGULARITY. Take the plugs out & roll the flywheel forward until the left side sparks. Roll it backwards 1/4 to 1/3rd of a turn then back forward to make the mag trip again & that left one should spark again. If you do this back and forth getting 10 impulse trips but you don't get 10 good blue sparks across the normal spark plug gap, service your mag!

Remember some choke can help make a tired mag's life enough easier that the engine may smooth out. Fuel may not be the problem and weak spark may be the culprit. That's why I check spark first.

If ignition proves to work well, take the intake elbow off of the front of the carburetor, pull the choke rod out to fully close the choke and peer down his throat with a flashlight. There is a "flapper valve" on the BACK side of the choke plate that covers a hole through the plate that is shaped much like a 500 gallon LP tank. Have seen flapper valves bent, missing or the spring that is supposed to hold them shut broken or missing and the choke is not choking it hard enough to get enough gas to start. If it's all there, take a pencil or small screw driver & poke at it a bit to make sure it is held shut with spring tension. It should not open freely!

Since you have to choke it to make it run smoothly it MAY be simply trying to run it with too lean a setting. Make sure the load needle (close to fan shaft) is 3/4 to 1 turn open & the idle 1 to 1 1/4 open! If it won't run like that without choke, it's time to work on the carburetor.

Another item I've encountered on the H is a manifold filled with deposits. Have found 'em that had burned gasoline for decades & the manifold cooked the lead or carbon or both out of the gas building up deposits in the manifold. Have seen the manifold choked down to a passage only the size of a dime. This reduced how well the carb worked because the manifold was as small as the carb's venturi. Won't pull a fat hen off her nest!

Hope that helps.

I had the same problem but learned I was moving the choke incorrectly. There is a line marked on the choke on the carb showing the plate position. Operates opposite of my US B choke. Helped it start better but still had Poppin John rebuild it. Its always started good but now the best of all my toys.

Mike the reason I think that in take leaks is more of a problem on the JD "H" is because of the smaller displacement. So leaks are a bigger percentage of the drawn air.