My friend has a 1985 Camaro Z28,
Specs:

305
5 spd Manual Trans

There appears to be a leak from the water pump, and when the engine is on, it leaks excessively causing temptures to rise from our perspective. Although the leakage is acknowledged most of the time while he is driving the tempature is an average degree, it is only at random times that the tempreture rises. Why is it at only random times the tempreture rises?

He also turns on the heater to help remove hot air from the engine compartment.

 

Replace the water pump. If it "pees" out the weep hole (small hole located on the under side of the snout), the guts of the pump are shot.

heater doesn't draw air from the engine bay. It draws from the cowl area.

 

Well for him it seems to work some what.. we will replace water pump and see what happends. as soon as we recieve funds.

 

Also, what type of water pump would you recommend for better performence from a 85' 305 Z28 ? any good ones you know??

 

I would attest the randomness to low fluid levels. There's air pockets throughout the cooling system that cause things to head up quickly, then the coolant hits again and cools it back down.

That's what mine does anyway when the coolant is low.