Originally Posted by t walgamuth
debris in the rad from the overheat?
Did you ever flush the engine? I have several of these engines and they run pretty cool in general unless blocked.
What have you done to clear out the block after 30 years of crud?
A good couple of citric acid flushes would probably help a lot. Directions listed in the forum. Use the search function.
Run the thing in place with the rad cap off each time you flush it.
How clean is the radiator?
Pull the external thermostat set-up and take a look at the inside. Is there gunk in there?
Do it all and report back. Good luck!