Overheating during cam break in

TrailBeast said
Especially with a flex fan and no shroud.

This thing has all the ingredients for getting hot on the breakin.
1. No fan blowing on it.
2. A flex fan
3. no shroud
4. Low timing
5. Minimal radiator

I'm not saying all the above should be done, but almost any single one of them done would probably solve the heat problem.

Also go ahead and drill that thermostat and put it back in.
Why have to concern yourself with air in the coolant ever, let alone on a stationary engine on a breakin.

I missed the flex fan part. The no shroud alone is a worry. The shroud is MORE important than the fan. Yes. Seriously. Flex fan doesn't help either. They are designed to not flow at high RPM. To save HP.

Ditch the flex fan (not just for break in, they are garbage anyways, ask the guys on here how many of them who know someone who lost a finger or more to one of them). Put on a solid fan, with fan clutch and appropriate shroud. You won't regret it at break in or after.