retard timing will make them heat up also.

make sure you have the correct # of vanes on the WP impeller

a/c wp = 6 vanes
non a/c wp = 8 vanes

a/c has 6 vanes with smaller pulley(spins faster) and pumps x amount at idle

non a/c has 8 vanes with larger pulley(spins slower) and pumps same x amount at idle

mixing the 8 vanes with small a/c pulleys can cause pump to cavitate at higher rpms and temps go up. or a 6 vane with large pulley it will not move enough water at idle.

make sure the lower hose is not sucking flat = add a spring inside lower hose.

make sure the fan clutch is spinning at correct speed all thru rpm range or just replace it with a new HD thermos clutch

just a couple things to check that I did not see mentioned.

good luck