Farmall Cub

Hi folks, new to the forum.

We've had a lo boy on our farm for several years, it's just been getting more use the past few years. I've got a few questions if you don't mind?

1. Does anyone know how many amps I could draw off the battery safely without fear of cooking the starter/generator? Years ago we burned it out when running a big electric pump and had to have something rewound, had a new regulator put on it, etc.

2. Is there a kit to switch to a regular starter / alternator setup?

3. Something might be going on with the governor - the engine will automatically move the throttle control (that you operate with your hand) back down to idle unless you hold it in place at a higher throttle setting. I've tried tightening the hinge for the throttle control but that doesn't help.

Thanks for any tips!

The service manual doesn't list the test amperage in the start mode for the starter/generator. The service manual lists the cold output as 25 amps when functioning as a generator. Guessing that the starter/generator will draw 50 amps, perhaps more, in the start engine mode.

No kit. There is a recent discussion on this board about installing a starter on a numbered Cub.

Not the governor. Need to repair or replace the throttle control lever.

Eugene wrote:The service manual doesn't list the test amperage in the start mode for the starter/generator. The service manual lists the cold output as 25 amps when functioning as a generator. Guessing that the starter/generator will draw 50 amps, perhaps more, in the start engine mode.

No kit. There is a recent discussion on this board about installing a starter on a numbered Cub.

Not the governor. Need to repair or replace the throttle control lever.

you won't find an amp draw spec specific to a starter motor. You can sometimes find an amp draw spec in a vehicle service manual but this is a test of the vehicle battery, wiring and starter. Starter motors are different than most other motors. They are series wound vs. Shunt wound. What this means is the field coil is in series with the armature as opposed to shunt wound motors that have the field coil in parallel with the armature. Series wound motors will draw as much current as is available. They are not self regulating, they will draw max amps at locked rotor or freewheeling, load or no load. If there is enough power available the motor will spin fast enough to either melt windings or blow up the armature. The reason series wound motors are used in starters is that they provide max torque at zero rpm.

chris95040 wrote:...Is there a kit to switch to a regular starter / alternator setup?

Check the mounting point where the starter attaches to the block. On a 154, the cross member that the rear of the engine attaches to will not allow the starter flange to seat against the block. The nose of the starter contacts the crossmember and modification is required to fully seat the starter against the block. I've not got far enough into it yet to determine how the ring gear will attach to the flywheel.

Oh, sorry, I wasn't asking how many amps the starter draws. I was asking if anyone knows how many amps I can draw off the generator. Does anyone know this figure? (I heard one vote for 25 amps?)

Assume the battery itself is at a full SOC and therefore isn't drawing much charge current.

chris95040 wrote:I was asking if anyone knows how many amps I can draw off the generator. Does anyone know this figure? (I heard one vote for 25 amps?)

You can double check my quote of 25 amps, service manual, GSS-1408, section 10.

The ignition system draws about 4 amps. The lights about the same just FYI