The Stovebolt Site Forums The Parking Lot Big Bolts 2nd Series '55 6400 350 swap

I used a heater valve from Napa (part # 660-1294), 4 ports, vacuum operated, goes inline. no vacuum, it allows water through to the heater core, add vacuum (for the summer) and it bypasses the heater core and allows water to flow back into the engine.