After many many years away from the old car hobby, I recently purchased a 51 Ford F1 pickup. It is all original, was stored in a barn, and was owned by a little old lady. The electrical wiring is pretty rough and I have been replacing some of it. It took a couple of days before I realized that the system was hooked up as positve ground. I do remember that Ford did this in their early vehicles but I thought that by '51 they had pretty well switched to negative ground. My question is: Has someone wired the truck incorrectly, or was the 51-F1 still positive ground. Second, does anyone know why Ford perceived the positive grounded stategy as "a better idea?"
Dave

 

My 53 f100 was positive ground so I think it is safe to say your 51 is too. I read somewhere where they were experimenting with the ability of the spark to jump the sparkplugs depending on the polarity. I think they figured out negative ground was best, but I don't know why they used positive ground in the beginning.

 

The last year for positive grounds was 1955. When they switched to 12V in 1956, they went negative ground. As for why they stayed with it, That's one of the mysteries of the ages!

 

The stock electrical system is 6-volt, positive ground. I've found it's only an issue when getting a jump start. As a side issue, you may want to run a ground cable from the block to the body. It seems to have helped my truck's electrical system.

Tony
F2H1SP24002