Originally Posted by Scrumgees
I have a 383 chevy stroker motor that really has no cooling problems but this gets interesting, trust me.
The water pump I have now is a stock long water pump with the bypass, the threaded port on the top of the pump body that is plumbed into the heater core or directly to the intake manifold, and is blocked off. I am not running a heater core or any other accessories plumbed into the coolant system. Be cool amuminum radiator, stant thermostat 180 degrees stat.
Everything worked well until i switched my pump to the edelbrock polsihed aluminum high flow pump to pretty things up a bit. The pump is the correct rotation direction, i have verified that, and is installed in the exact same configuration as the old pump. Now the engine will not flow a single drop of coolant and skyrockets to 250 no problem. when I remove the thermostat the pump flows like a champ, and i cant get it above 140 degrees. I have verified the function of the thermostat aswell as tried several other thermostats. Upon putting the old pump and thermostat back on, everything works fine again.
I am planning on trying one of the Mr gasket or the EMP/stewart high flow stats with the bypass holes in them. I have even replaced the pump under warranty and the problem persits.
I phoned edlebrock and knowone had any what to do, or any useful information.
Has anyone else had this problem?
Dont stock pumps have an internal bypass circut within the pump body? Does anyone know it the edelbrocks have this internal bypass aswell?
If this does not work, im just gonna replace it with a stewart pump When i phoned them, they actually knew what they were talking bout.
I run the same pump on my Frankenmouse, but I painted it black. It is bypassing thru the heater and has no problems.
It sounds like your configuration has the pump deadheaded, which might indicate the right side bypass in the casting isn't functioning or isn't enough of a bypass for the Edlebrock pump. These high flow pumps use a different design impeller from the OEM and may need more bypass to keep from stalling. I'd plumb the bypass from manifold to pump in preference to drilling holes or at least very many or large holes in the thermostat. The hosed bypass lets the pump circulate coolant thru the block and heads when the thermostat is closed. This heats the engine up faster than running even small amounts of coolant thru the radiator when cold as the holes in the thermostat will allow, this gets the carb or injection off "choke" more quickly to reduce fuel wash of the lube from the upper cylinders. This also uses coolant flow to eliminate local boiling which especially is problem with the paired exhausts as this is a lot of heat in a small area, this spot can be flaming hot while the rest of the engine is cold, in turn it leads to cracked castings, warped valves, seats that fall out of aluminum heads, and not so pleasant things like that. Seems like if this is a motor that's on show in a coupe that a bypass with some AN fittings and stainless wrapped hose would offer that polished industrial look while doing something practical.