47 farmall a hard start

[Jack jr]

G'day I have a 1947 Farmall a that is temperamental,
It will sometimes sit for 2 weeks I will give it 2 cranks with choke 3rd without choke and it will go, then you will shut it off for any amount of time try start it and it wont start on the crank no matter what you do, but if you roll start it it will go within 6 feet and run fine, temp seems to make no difference I changed the condenser, points, cap, rotor, plugs and it made no difference sometimes it go's sometimes not without a roll start,
I have to crank it very slowly to get the impulse coupling to work but it will start like that sometimes.
i am at a loss with it.

Cheers Jack jr

[Jim Becker]

STOP.

Do not try crank starting until you get the impulse coupling fixed. The risk of a kick-back and consequent broken arm is too big.

Your starting problem has all the symptoms of a non-functioning impulse coupling. So dealing with the impulse coupling will probably cure your starting problem.

Again, do not try crank starting until you get the impulse coupling fixed.

[Jack jr]

G'day Jim thanks for the reply I will check but I believe the impulse coupling is working as you can crank it as slow as you want and you can hear it click and get a good spark should the impulse work on all 4 cylinders or just 1 and 3.
Cheers Jack jr

[Jim Becker]

It should work the same on all 4 cylinders. The coupling has 2 pawls, one engages the stop pin for cylinders 1 and 4, the other for 3 and 2.

[Jack jr]

Ok so one of mine isn't engaging I have never pulled one apart is there anything to be aware of or a the relatively simple thanks for you help.
Cheers Jack jr

[Jim Becker]

You need to look at the Magneto Service Manual in the PDF manuals. (Quick Links at top left of this page). Go to PDF Manuals, Service Manuals, Blue Ribbon Service Manuals, GSS-5035 Service Manual Magnetos. There is a section on the H-4 magneto, which I assume is what you have.

Unfortunately, you about have to have a special tool to remove the coupling from the magneto. To make magneto installation easier, follow these steps for removal:
- Slowly turn the engine by hand until you hear the impulse click.
- Remove the distributor cap and make note of the direction the rotor is pointing.
- Remove the magneto. Do NOT turn the engine while the magneto is removed.
- To install, turn the magneto backwards until the rotor points in the direction previously noted.
- Use the book procedure to time the magneto.

[Jack jr]

G'day I pulled the impulse apart and but couldn't find anything broken, the springs seemed very loose and i may have upset them pulling it off they are a bit rusty, I have looked around and don't seem to be able to buy any in Australia does anyone have any idea where I could get 2? Tractor still starts if you roll start it or crank start it pulling the crank quickly.
Cheers Jack jr

[Jim Becker]

Look at the stop pin and the very corner of the pawls where they engage the stop pin. They may be worn enough so they don't engage reliably. A worn pin can probably be knocked out and reinstalled at a half turn to get a new surface. Wear at the pivot point of the pawls may be a problem too.

Reread my cranking comments in my first post.

[Jack jr]

G'day I pulled the impulse apart aging and got it working better with a slow crank I have a big blue spark, still only starts sometimes on the crank I recently changed with 20 year old plugs in it to some champion d16 the tractor doesn't work very hard just road runs and pulling trailers mostly are these plugs to cold? cheers Jack jr.

[Gary Dotson]

They are not necessarily too cold but you might get a little better performance from D-21’s.

[Jack jr]

G'day I've been busy with other stuff and haven't had much chance to look at the tractor, it seams to start better with the throttle fully shut all I can think is the air is moving much faster past the idle jet pulling fuel up, I'll pull the carb down hopefully there is just some dirt or vanish thanks for everyone's help.
Cheers Jack jr

[Jack jr]

G'day I pulled the carb down last night and found no problems,
I cleaned it and refitted it, to run the tractor need the mixture screws out a lot of turns
and is still hard starting could this be a leaking intake manifold gasket?
thanks for all your help.
Cheers Jack jr