I see this problem constantly with guys that blame the warm Flathead for not starting. Most if not all the problem is that the battery cables are the vilian.

There is also proper timming, and carburator issues involved. I myself have run Flatheads for quite a few years, and have had no problems with the 6 volt system.

I have seen many people that after a 2 hour run as an example, stop gor either gas or lunch or whatever. The truck has sat for maybe 1/2 hour, first thing they do is turn on the key give it a pump and choke the hell out of it, and there they sit. This is where the 12 volt fix comes in usually.

Leave the choke and gas pedal alone with a warm Flathead. Also as far as battery cables go, use the proper ones. I myself make my own with welding cable size 1/0 use soldered terminal ends, and make sure the connections are all clean and tight. It makes a big difference, and of course I also use a good quality Agriculture battery, mine is 925 amps.

In closing, yes there are always maintenance issues like starters needing attention, carbs, timming, points, etc. So those who are useing the off the shelf Battery 12 volt cables for the 6 volt system, it doesen't work. I hope this little speil does help some, good luck.

 

Yep, thats been mentioned on here many times along with cleaning all ground connections, especially on the frame. I elected to not use the frame as the primary ground from the under floor battery on my 54 and went with 00 cable right to a starter bolt and then to the frame. Made a nice improvement. Also tied the firewall, inner fenders and headlight supports to the block with flat braided cable. Almost no headlight dimming even when it was still 6V.

Large 0, 00 and 000 cables are available at tractor and truck supply places. They come in many premade lengths or you can make your own.

For the non 12V diehard there are 8V tractor batteries available as well as adjustable regulators. Its rough on headlights and bulbs but its easy enough to make your own dropping resistors from discarded heating elements in home heaters or dryers.

My 53 Vicky with a 286 flathead is still 6V and turns over/starts very nicely with good fat cables and clean grounds.

 

Yep, I believe I have put it on here or suggested it to a few before. Those 12 volt cables just don't work well on a 6 volt system.
As for the 8 volt you suggested, been there and its a pain in the butt, your working the hell out of your generator and for what?
If the proper guage cables were used then the problem is in most cases fixed, as long as all else is in good working condition.
The flat ground cables you mentioned are a very good source as well, I also use the same method,