In Reply to: Questions about Square Coils posted by Farmer Dan on December 03, 2018 at 17:32:02:
I had a picture of JMOR's coil test circuit but can't find it. I believe the 6V front mount square can coil should read 1.3-1.5 Ù static measuring pigtail to top terminal post. FWIW: A 12V coil should read about double that reading. Make sure your VOM is set to the RESISTANCE (OHMS) scale. Polarity doesn't matter. That being said, I also believe that test doesn't necessarily mean the coil is good. Once it gets hot, it can fail and short out. Additionally, from what I've been taught, if the key switch was left on at some point, and the pints were closed, the coil could possibly melt the internal tar insulation thus creating the short. Once it cools down, the coil may work but as soon as it gets hot again, it loses its insulating ability and shorts out. I have a box of old coils, some OEM with the FORD script on top. Last summer when I did a tune-up on my '48 8N, I was tightening the coil terminal post nut and snapped off the stud off. I tested an old used coil from my box, had 1.5 Ù reading on it, installed it, and it worked fine and is still on the distributor. I know you have a solution for snapping off studs too with a quick disconnect tab. Here are some pix of a fixture I made for you to secure the distributor while doing a tune-up. I'll bring this with me as well next visit.
FORD TRACTOR FRONT MOUNT DISTRIBUTOR TUNE-UP FIXTURE: