Description
VALVE ASSY, Distributor Vacuum Control, 3 port, mounts to thermostat housing, exactly like the original without the original markings (has small *IH* logo),Made by the original supplier on the original tools with correct finishes,Missing only the correct markings,See 980-4 for installation tool,** Note: We have found that most of these valves are activating at around 125 degrees instead of the intended 225 degrees,What does this mean?At idle, under normal engine operating temperatures, the distributor advance (center port) runs off of ported vacuum from the carburetor (upper port) which is 0 psi at idle,During extended idling, on a hot day, maybe with the A/C on, engine temps can start to rise,When the coolant temperature exceeds about 225 degrees, this valve closes the ported carburetor vacuum port and opens the non-ported vacuum (lower port) from the intake manifold,Non-ported vacuum at idle is normally high (12-15 psi), and this causes the distributor vacuum advance to advance the timing which results in an increase of the idle speed (about 100 rpm), spinning the radiator fan faster and drawing more air through the radiator helping to cool the engine,When engine temps reduce to a certain point, the valve closes and resumes using ported vacuum,None of this effects the engine while driving as the distributor is already running an advance to the timing as speed increases,**
NPD Part Number : 12A091-8A
Manufacturer Reference ‘s:C8AZ-12A091-A, MY126, C8AZ-12A091-A, D5VY-12A091-A, D7AZ-12A091-A
