max water presssure

[Lotus 50]

How much water pressure is too much? The gage pegs at speed, but never goes below 15, even stopped.
1990 XR4

How hot is too hot? I ran hot for probably too long last week. I was stuck in a speed limit zone with a motor that would not stay cool below 40 mph. Is there any damage I should look for?

 

[FLYING BUTCHER]

you have blockage somewhere most likely the drain holes in exhaust plate but could be in water impeller or water jackets in heads poppet valve start with the easiest good luck better pull heads at least to look at cylinders and pistons