Matt Wozniak
My SPF 1049 had a "similar" problem when I bought it used from the first owner. The problem was self-induced.
Of course, I had to check everything before I took my first ride. The coolant was down a little, so I filled up the metal expansion tank. After a ride, I came back about an hour later and there was coolant on the ground, so I'd add more water. Same problem. It never overheated.
So I left it alone, and the problem disappeared. The metal expansion tank runs to a metal overflow container. When everything is right, there is some air space in the exansion tank, and there is some water in the overflow tank.
But that is not your problem . But my SPF also has a 7 lbs rad cap (CST T-7), and I have a small block. There also is a hose running from the expansion tank to the block. Yours may be different.
You could have trapped air in the block too, but I'm not that familiar with big block cooling.
You should call your local rep and discuss, especially if he installed the motor and transmission. Also, Bill Wells comments are absolutely correct. The last thing I would change is the radiator cap.
My water and
oil track each other, and normally run at 80 C. The fans are supposed to come on at 95 to 97 C. You might want to throw the dash switch so the fans stay on all the time and let the engine warm up on the driveway. Then turn the fans off and shut the engine off and see what happens.
All of the other feedback is good stuff to try.
2000 miles for me and never overheated .....
Hope this helps.