MSD 8489 Chevy Crab Cap Crank Trigger Distributor Installation - Manual (Page 2)

2 INSTALLATION INSTRUCTIONS
M S D
• W W W . M S D P E R F O R M A N C E . C O M • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4
Figure 3 Checking Oil Pump Shaft to the
Distributor Shaft Overlay.
REMOVING THE DISTRIBUTOR
1. Remove the existing distributor cap without disconnecting any
of the spark plug wires.
2. With the cap off, rotate the engine or until the rotor is aimed at a
fixed point on the engine or firewall. Note this position by making
a mark (Figure 2).
3. Place the distributor cap back on and note which plug wire the
rotor is pointing to. MARK THE SPARK PLUG WIRES and remove
the distributor cap.
4. Loosen the distributor hold-down clamp and slide the clamp
out of the way.
5. Lift the distributor out of the engine. Note that the rotor rotates
as you lift the distributor out. This is due to the helical cut gear and
should be taken into consideration when installing a new distributor.
PREPARING THE DISTRIBUTOR
The MSD Billet Distributor features an adjustable slip collar. This collar provides an adjustment to
accomodate variations in block height, modified intakes or heads. It is recommended to check the
slip collar setting before installation. MSD offers a special tool, the 3-In-1 Distributor Set Up Tool, PN
8599, to make these adjustments accurately. If the tool is not available, follow this procedure.
ADJUSTING THE SLIP COLLAR
1. Loosen the slip collar and insert the distributor into the engine until it bottoms out against the oil
pump drive.
2. After it bottoms out, raise the distributor 0.010" - 0.030" then slide the slip collar down into the
position and tighten it.
CHECKING THE OIL PUMP TO DISTRIBUTOR SHAFT OVERLAP
The proper overlap between the distributor shaft and the oil pump shaft is very important. The tongue
of the distributor shaft should fit into the groove of the oil pump shaft by at least 1/4". To check this:
CHECKING GEAR MESH
It is recommended to check for proper gear
mesh between the cam gear and distributor
gear. To do this, coat the distributor gear
with moly grease and install the distributor.
Figure 2 Marking the Rotor Location.
1. Measure the distance between the base
of the slip collar to the tip of the distributor
shaft (Figure 3).
2. Using a straight edge, measure the
distance from the intake manifold
distributor flange to the top of the oil pump
intermediate shaft (Figure 3).
3. Take the two measurements and subtract
them. The difference is the overlap. If
there is not enough clearance or too much
clearance, a different oil pump shaft is
required.