51 Model A Hard Start

I recently replaced the magneto on my 51 Model A and the tractor is very hard to start. It will crank and crank and crank. Blow some white
smoke. Crank. Blow a rafter shaking POP out the exhaust. Crank. Then randomly catch and fire and run. Once running it runs good, fires on
both cylinders, but not great. It is very sensitive to changes in speed/load. I need to feather the clutch just right to move and even
pushing the throttle too fast can kill it. Then the cranking starts all over again. What am I missing? Am I still out of time? Do electric
start tractors with mags prefer spark more advanced or retracted? I assume tilting it towards the front advances it? Carb is clean but could
something have gone wrong in there? Could a component of he mag gone out already?
I'm looking for a direction to go because the tractor just isn't fun to use right now and I use it a lot for tilling, planting, cultivating
and picking in the fall.
Thank You.

Sounds like it isn't timed right.

swap your two spark plug wires at the magneto and try it.

I'd be interested in your old magneto if you still have it.

Dirk you ask 'Do electric start tractors with mags prefer spark more advanced or retracted?'

They like to start at TDC and as far as run timing that depends on which drive cup your mag has such as a 25 or 35 advance etc., points gap, plus the mags into the governor rotation timing which CCW backwards advances and CW forwards retards. Rotating the mag affects BOTH start and run timing. For gas operation I dont like much over 25 BTDC unlike an older all fuel when running on lower octane distillate or kerosene where 35 BTDC may be better....... TIMING MAY WELL BE YOUR PROBLEM or at least a part along with carb settings and ignition quality

The carbs idle as well as fuel needle setting may need adjusted also, maybe needs to be opened richer for better throttle response ?? A good fresh set of plugs may be in order as well as a general ignition tune up such as points and points gap and plug wires??

John T

Whats the history on the magneto you installed? It sounds like weak spark running on one cylinder. How about the spark plugs?

You might consider adjusting the magneto timing.

Reviewed the [b:654c4848f0]OPERATORS MANUAL No. OM-R2002R JOHN DEERE MODEL A SERIES (SERIAL No. 648000 AND UP) TRACTOR[/b:654c4848f0] in the [b:654c4848f0]IGNITION SYSTEM[/b:654c4848f0] section under the [b:654c4848f0]Installing Magneto on Tractor[/b:654c4848f0] topic on pages 34-35.

[i:654c4848f0]Installing the magneto after it has been removed from the tractor can be done easily as follows: First remove the spark plug on the flywheel side.



Place your finger over the hole and rotate the flywheel in the running direction until you feel a pressure of air in the cylinder. Continue turning the flywheel slowly until the punch mark stamped on the flywheel hub, lines with the V grove on the flywheel guard.



In this position the slot in the coupling on the governor shaft will be horizontal.



Next secure a short piece of wire and insert one end in the upper terminal of the distributor cap on the magneto, bend the other end around within 1/8-inch of some metal part of the magneto.



Hold the magneto solidly in the same upright position as when mounted on the tractor.

Grip the driving lug on the impulse coupling firmly and turn the impulse slowly in a left-hand direction (counter-clockwise). Stop instantly when impulse trips and spark occurs between end of wire and magneto frame. When impulse trips, driving lugs on the magneto coupling will be in a horizontal position.

Replace magneto and gasket on the governor case, making sure the impulse coupling lugs engage slots on the governor drive coupling.



A gasket must be used between bolting flanges. After tightening the two cap screws firmly with fingers, rotate the top of the magneto toward front of tractor as far as possible. Then rotate the flywheel one complete turn and line the punch mark on flywheel hub exactly with the V groove on the flywheel guard.



Now tap the top of the magneto toward the rear of the tractor a little at a time until the impulse trips.

Tighten the cap screw holding magneto to governor case and install spark plug cables. Left hand spark plug cable must be installed in upper distributor cap terminal.



[b:654c4848f0]Caution: Whenever adjustments are made on the tractor engine, remove the spark plug cables from spark plugs and battery ground cable to prevent accidental starting.[/b:654c4848f0][/i:654c4848f0]

Hope this helps.

I have had issues with starting my 36A after having the magneto off. This was an operational and correctly timed magneto. If reinstalled with the old gasket (or a new one that seems a little thin) I have had them bind the starting advance and backfire (out the intake not the exhaust) while cranking. I have even run two gaskets in the past just to avoid this issue.

As far as I know the 51 did not come from factory with a mag, only a Delco distributor. I had a 51 with that distributor. Ther 49 be came with a mag and I think 50 was last year for a mag. If a Wico they can be confused with a mag.

Did you have any luck figuring out what the issue was, if you do please let us know. It always seems on my tractors it is something simple just takes a while to find it, good luck

Thank You All for the Help.
Taking all the below advice I made several adjustments. I was WAY out of time and my ideas of advance and retard spark were opposite what I learned here. So I made the appropriate changes and timed it like a hand start with the flywheel cover off based on an old timer I know and some you tube videos. Adjusted the carb to 1 1/4 turns to start. Then I will make adjustments once warmed up.
The funny thing is I was literally ready to turn on the gas and hit the lever when my boys came in. 7 and 2. They have a passing interest in tractors and do not like how loud the tractor is inside the shop during start up and besides that, wanted to play. So I went and played and never got back to the shop rest of the weekend.

You got your priorities right there Dirk! Those boys will age alot quicker than the 51 Model, so keep focused on them to keep em running right!

I have a 51 A built August 7 of 51 that my dad bought new in October of 51. I was 8 months old at the time. I am pretty sure I remember dad saying he had the mag removed and a distributor installed. What makes me dubious of this is the primary wire and the crimped ends look like factory, not like some shop job. Maybe the distributor came as a factory made kit?

Tractor was WAY out of time. It started on the second rotation of the flywheel. I had quick reaction on throttle, power. It became my favorite tractor again. amazing that it ran at all as badly as I had it timed. Thank you all for the advise.