PerTronix Dougs Headers D3367Y-4 - Manual (Page 8)

Part No. 0110-003018
Page 8
Rev 2 3-5-13 DSL
AIR INJECTION LOOM INFORMATION
Note: Should you require replacement of the stock air injection looms, your local GM parts
department may be able to provide replacement air injection looms using these part numbers:
Dual AIR Pump
Single AIR Pump
Driver side: 14102115 Driver side: 330544
Passenger side: 14102114 Passenger side: 330544
HEAT RISER INFORMATION
What is a heat riser?
The heat riser is a valve that closes off the exhaust on one bank of a V8’s cylinders when the
engine is cold. This routes the hot exhaust gases from the closed-off bank through the exhaust
cross-
over at the center of the intake manifold and out through the exhaust manifold on the “open”
side. The exhaust heat helps the gasoline in the cold intake manifold reach evaporation temperature
more quickly, eliminating “puddling” of raw gasoline in the intake manifold and making the vehicle
much more driveable when it is cold. As the engine warms up, the valve opens, allowing the
exhaust to flow out through both headers.
What is an “E.F.E. valve”?
“E.F.E.” stands for Early Fuel Evaporation, and “E.F.E. valve” is often considered to be another
name for the heat riser. Some vehicles, however, have what is referred to as an “E.F.E. system”.
An E.F.E. system might include both a heat riser in the exhaust manifold and a hot air pickup that
draws the en
gine’s intake air across one of the exhaust manifolds to preheat it during cold start
conditions. Whatever combination your vehicle came equipped with in its stock configuration is
what must be reinstalled and reconnected when headers are installed in order for your vehicle
to be smog legal. If in doubt, consult your new-car dealership parts department or an authorized
smog inspection/maintenance station.
What controls the operation of the heat riser?
There are two types of heat risers: mechanical and vacuum. The mechanical types use a bi-metallic
strip which works like a heat-sensitive spring, opening the valve when it gets hot enough. The
vacuum type uses a vacuum canister similar to the vacuum advance on an ignition distributor.
Vacuum routed through a heat-sensitive switch (usually monitoring engine coolant temperature)
pulls the valve closed when the engine is cold, and then allows it to open by shutting off the
vacuum supply when normal operating temperature is reached.