Tommyboy
First fire up for an engine, they very often run much hotter than they ever will again. I have seen ceramic coated headers glowing, only halfway through the cam break-in process. (I think it is excessive heat being created by the piston-ring friction with the freshly cross hatched bore) Anyway, I would always break in cobra motors with fans at either sidepipe exit, and when the headers got too hot, shut it down and resume again after it had cooled a bit. The
oil and water wouldn't get too hot during this phase however. If you can shove your hand most of the way between the body and the sidepipe primaries, you are OK for clearance, my knuckles don't fit though.