The story gets another chapter.
I got the upgraded stage 4 Stewart pump back, put the car back together, and took it for a ride. Got maybe 5 miles on it, and jumped on it in 2nd gear. Ran it up to maybe 5 grand. A minute later, noticed the gauge was at 210. Pulled to a side street & popped the hood. Was greeted to a motor covered with anti-freeze, and a gusher spraying from the pump. When it slowed down, I could see it had blown the gasket for the rear plate of the pump.
Another 2 hour disassembly (I'm getting good at it) revealed this...
My motor builder had tried to warn me NOT to run a thermostat, especially with the upgraded pump, saying we don't need one, and it is too restrictive. He says we control water temp with the electric fans, and the thermostat needs to go.
The pump obviously made so much pressure, something had to give. I have no other idea how to eliminate the pressure other than to ditch the 'stat.
I made a new gasket, glued it in place with Hi Tack, and put it back together. this time WITHOUT the stat. Drove it about 5 miles, it ran up to about 180, the fans kicked on, and dropped it back to about 170 (where they are set to turn on & off). So far, so good.
Of course now I'm gun shy, gonna stay close to home until I get a few more miles under my belt.
In the meantime, I hope I don't get a ticket for inattentive driving while fixating on the temp gauge!
I hope this is the end of the story....
Bill