Hello SF Man, My '53 JD 40T is draining the battery every time after 1st initial crank on fully charged battery. Now this same battery easily cranks over my dads Farmall Super C; which is similar sized tractor. I can pull start it and it will crank up & run very smooth. It has new switch, points, rotor, cap, spark plug wires, spark plugs, coil, starter-battery wire, ground-battery wire, and all new wiring. Verified that points & spark plugs are gapped correctly, plugs throw spark in/outside of engine when it turns over. We are just baffled at this point and not sure how find/fix this issue. Our only next was to run two 6 volt batteries n parallel to achieve more CCA. Any thoughts or help would be much appreciated as this a father & son project.
Well I'm not the Shell answer man here - but your problem sounds like the one we had with our IH 400 - great old tractor - but it was a 6 volt system - if it did not start are the 3rd UUURRRRR - then she was done - I changed everything , then one day talking to a well seasoned mechanic - he said the 400's were a high compression motor - 6.3 to 1 If I remember right and it just didn't have enough volts to spin it - the only fix was to put a 12 volt system on it - and that is major - new starter , battery + what ever , So I took a few minutes and pulled up the spec.s on a 40T Motor - it has a 6.5 to 1 compression - and your Super C is only a 6.0 to 1 - That may be why your battery spins it OK - This only a guess of mine - Good luck