ron blair,

Welcome to the Stovebolt. Your starting system must be pulling a ton of current somewhere. Are your cables new and properly sized?

Did you really find a 12 volt starter for your 216? If all the cables and connections (clean ground to frame and engine) are clean and good, it sounds like there could be a mechanical issue that is causing the engine to drag and force the nice new starter to work to the max. It seems strange for the weak link to be the big cable connection on the battery.

Is the new 12 volt replacement coil internally resisted or did you install some type of bypass/resistor circuit. Those points won't want a full 12 volts for long.

I would clean both battery posts well, clean the cables and stick them on tight and make sure they are clean and tight on the starter and to the ground point.

When your crank your engine, a huge amount of current flows and it can cause heat but it would be more typical to heat a connection ON the starter itself..or the starter.

Keep looking and keep us posted.

Stuart