Originally Posted by mightycarlo10
I pulled the ac/heater blower unit box thingamajig out of my 87 Monte Carlo and put in a 383 and TH350. My question is can i just connect the two coolant lines that go to the heater core. I have heard people just blocking the ports, but i thought that the heater core and lines were important because when the thermostat is closed, thats where the coolant flows and circulates.
You'll have to cut and try, some SBCs are really sensitive to the heater circuit as a bypass, others are not. In theory, there is a bypass hole below the the right side water pump mounting horn. This is supposed to provide a bypass when the thermostat is closed. It often is insufficient to keep the pump from cavitatng and hot spots from local boiling. The pass through the heater or a simple bypass loop without the heater insures this won't happen.