Hot Rods Early Hemi BB Chevy waterpump pressure buildup problems

I run a short style Weiand big block chevy waterpump with Hotheads adaptors on my 354 Hemi. No heater, so the heater hose outlets are plugged on the waterpump. Problem has been when you run her hard thru the gears the water pressure builds up and pops a frostplug or the back gasket on the waterpump. Lately I've just run a washer in place of the thermostat , no difference pressure builds and pushes something out. I've heard that running the heater hoses to a heater helps but I don't have a heater nor want one at this time. I know Hotheads sells frostplugs that won't pop out but the pressure will blow something else out. Any ideas, pointers much appreciated. thx

 

as a test,you could install a loop of heater hose from the pump to the intake manifold. It sure seems that the pump is pushing more volume than the cooling system can handle. Slowing the pump down with different pulleys perhaps

 

I hate to say it, but your problem sounds to me like a leaking head gasket allowing exhaust pressure into the cooling passage. Water pumps by design shouldn't make enough pressure to blow anything out.

 

The bypass port on the BB pump. I run it into the head crossover.

 

Something sounds wrong, if pressure exceeds the value of the radiator cap then it opens and sends fluids to the overfill. That should happen way before you pop a freeze plug or waterpump gasket. If this is a new combination then you're probably going thru 'new car blues' sorting out all the bugs.

 

a picture should help