ZZ502 Component Information
Ignition System
The HEI distributor (Part Number 93440806) included with the ZZ502 deluxe engine is a self-contained ignition system that
includes a magnetic pickup, a module, a coil, a rotor, and a cap. The HEI’s large diameter cap minimizes arcing and cross
firing between adjacent spark plug terminals. The cap’s male terminals provide a reliable, positive connection for the spark
plug leads. However, the HEI’s large diameter cap may interfere with other underhood components in vehicles not originally
equipped with HEI ignition systems. Check for adequate clearance before installation. The HEI distributor supplied with the
ZZ502 deluxe engine has a hardened drive gear that is compatible with a steel camshaft. Use of a non-hardened distributor
gear will result in excessive wear.
The HEI system requires a 12-volt power supply for proper operation. The HEI ignition system should be connected directly
to the battery with 10 or 12 gauge wire through a high quality ignition switch. If you are installing an HEI ignition in an early-
model vehicle originally equipped with a point-type ignition, be sure to remove or bypass the resistor in the wiring harness to
ensure the HEI receives 12 volts continuously. Use distributor connector package Part Number 12167658, which includes
connectors and wires for the HEI’s tachometer and 12 volt terminals.
Water Pump
The ZZ502 deluxe engine comes with an aluminum, short style water pump, Part Number 12494151. The pump included
with this kit has a standard rotation impeller that is used with conventional accessory drives. Some serpentine belt systems
require a water pump with a reverse-rotation impeller. In these instances, install a water pump specified for the original
application.
Timing Information
Set initial spark timing at 10º before top dead center (BTDC) at 650 rpm with the vacuum advance line to the distributor
disconnected and plugged. This setting will produce 32º of total advance at wide-open throttle (WOT). The HEI vacuum
advance canister should remain disconnected. This engine is designed to operate using only the internal centrifugal
advance to achieve the correct timing curve. The HEI distributor supplied with the ZZ502 deluxe engine has mechanical
centrifugal spark advance with the following curves:
Mechanical Advance:
RPM
Advance
1100
0.0º
1600
12.0º
2400
16.0º
4600
22.0º
Carburetor
The carburetor included with the ZZ502 deluxe engine is a Holley 4-barrel Model 4160 dual feed fuel inlet, vacuum
secondary carburetor. This carburetor features center hung float bowls, electric choke, power valve blow-out protection, and
a secondary power valve. It has the correct calibration for ZZ502 crate engines. For more information and carburetor set up
instructions, see the specific carburetor instruction sheet or visit www.holley.com.
Air Cleaner
The ZZ502 deluxe engine does not include an air cleaner assembly. Chevrolet Performance Parts has two chromed, 14-inch
diameter, open element air cleaner assemblies for single four-barrel carburetors. Part number 141-306 available from our
licensed partner www.factoryperformanceparts.com, has a plain top and part number 141-302 available from our licensed
partner www. factoryperformanceparts.com, has a Chevrolet logo. Both of these assemblies are supplied with a 3-inch tall
filter element, part number 6421746 (AC# A212cw). A taller 4-inch element is available, part number 8997189 (AC# A698c).
