[Steves46]

I had the same problem when I used to own my 46 Ford (Flathead V8 & 6 volt positive ground). Changed the battery cables to 00 gauge and noticed immediate improvement. Later-on the starter started to slow down a bit but after a starter rebuild, everything was good again. So, if your cables are already proper size, I would suspect the starter may be getting tired and needs a rebuild or replacement. If the cables are small, try replacing with larger cables first. Hopefully you will resolve the problem soon.