Back in the middle 1960`s I dropped the 312 into the 55Tbird and converted the electrical system to 12 VOLT Neg ground. Used a Ford 12 volt gen I bought.

I HAVE NOT used the 12 volt starter I bought at that time. AND I NEVER HAD TO. That starter is still on my garage floor.
This advice to limit current flow to the starter by changing battery cable size is beyond my comprehension. That is not how electricity works. Larger cable = lower RESISTANCE,
lower heat MORE ELECTRICAL ENERGY delivered to the starter from your battery.
On another car OLDS, long gone I had hot start issues until I retarded the ignition timing at engine cranking to start. Then at cruise NO LOAD the ignition timing approached 45 degrees BTDC
and I would run it like that until I had another CA SMOG check ( every 2 years ) This was MANIFOLD VACUUM not ported vacuum. RAN GREAT. Pete

My car is a 1955 TBird.  Obviously it had a 6 volt electrical system from the factory.  Before I bought it, a previous owner converted it to 12 volts.  They left many of the six volt components.  When I purchased the car, it still had the positive ground. I swapped the cables around and repolarized the voltage regulator to a negative ground.  My car currently has a six volt starter and it works great with the 12 volt battery.  The only thing that I did not reconnect was the radio and the clock.  I suspect they will work, but I haven't tried them yet.  The 6 volt generator worked also, but it was weak.  I recently upgraded it to an alternator.  All my gauges and lights work.  My O/D works and I have no other issues.  6 volt wiring is much larger than 12 volt wiring.  I saw no reason to change it.

Back in the early 60s I bought a ‘40 Ford pickup that had been converted to 12V, with a ‘48 Merc flathead stroker motor in it that had never been started (built originally for a sprint car). It had chrome rings & HC heads, and an inscrutable magneto ignition. I never could get it started, but I burnt up a half dozen 6V junkyard starters in the attempt. Just be aware that if you develop some issue that makes the engine very hard to start, a 6V starter is likely to fail way before you can run the battery flat.
P.S. I heard the guy I sold that pickup to eventually started it by pushing it on a country road in second gear for several miles. Likely just far enough to finally seat the rings.

6 VOLTS/POS. GRD. NW INDIANA

Daniel from what you write I am left with the feeling it had NOTHING to do with the starter being 6 volt. It could have been 24 volts, just too much
internal friction in the engine, A high school friend had a 31 Buick straight 8 and after re ringing it we had to tow it in gear for miles to get that thing
free enough for the starter to even budge the crankshaft over. Pete

I really don't understand your question - are you worried about using the 6 volt starter?  Wire size?  I had a 53 flathead, 12 volt, 6 volt starter.  Didn't have a problem with the starter burning out


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

I’ve used 6 volt starters on 12 volt systems without issue but I’ve always used the larger 6 volt starter cable to insure adequate amp draw to the starter.  If you have to grind on those 6 volt starters for any period of time without giving it a break, they will eventually give up.  I have had issues with the bendix failing prematurely usually due to the 6 volt starter engaging more harshly but even that took some time and doesn’t happen right away.  Usually when that happened, I went ahead and switched to a 12 volt starter and went on.

Lorena, Texas (South of Waco)

when i owned a 55bird, 15years back all 6volt,had the radio rebuilt,the guy inst a electronic vibrator,as soon as i reinstaled it screwed the vibrator, as he was not aware of positive ground. so if your radio is or has bin repaired,that will be a issue.. there is a with that acomedates pos grad to neg for radio and clock. can't recall where they are sold.
re first start ups the solution is have some primer fuel with some engine oil mixed this gives the new rings and saves some lube on 1st start.

Engine starters are not designed for continuous duty, nor are solenoids or starter relays for that matter. A relatively small motor can turn over a large engine if it normally only takes a second or two at most and then isn't needed again for some time. When everything is in good order and engine is in satisfactory tune this system works very well.

Engine starter duty cycle is something like 10 seconds on, 30 minutes off When you hear someone grinding and grinding away on the starter for 30 seconds a pop over and over, that is the death knell for that starter. To me, it is cringe inducing. I don't beat horses or animals and abusing machinery is almost as bad to my mind.