Here's what I have tried:
Replaced entire water pump kit w/ new impellor
Replaced thermostats and poppit valves
Removed cylinder heads and replaced water diverters
Forced high pressure water through copper tube
Cleared small hole in thermostat housing
Notched the poppit valves
It will run at 4200 rpms for over an hour with no issues, but at 4500 rpms it overheats in about 10 minutes. The motor was trimmed down.
Replaced entire water pump kit w/ new impellor
Replaced thermostats and poppit valves
Removed cylinder heads and replaced water diverters
Forced high pressure water through copper tube
Cleared small hole in thermostat housing
Notched the poppit valves
It will run at 4200 rpms for over an hour with no issues, but at 4500 rpms it overheats in about 10 minutes. The motor was trimmed down.