MSD 8381 Installation

MSD Pro-Billet LT-1 Distributor

'93-'94 F-Body, '92-'94 Corvette, '92-'94 Full Size

PN 8381

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Parts Included:

1 - Distributor
1 - Cap
1 - Rotor
1 - Isolator

IMPORTANT: Due to the number of applications and years that the LT-1 Distributor is used on, it is highly

recommended to have the Service Manual for your vehicle during this installation.

IMPORTANT NOTES BEFORE INSTALLATION

Throughout its
course, the GM
LT-1engine used
two different
drive mecha­nisms to con­nect the cam to
the distributor.
Figure 1 shows
the drive for the
MSD PN 8381
Distributor. This
design is used in
the early model distributors. Make sure this is correct for your application.

2 - Rotor Screws
1 - O-ring

3 - 1/4-20 x 2" Socket Head Cap Screws

STOCK DISTRIBUTOR

Figure 1 The Drive Mechanism of the PN 8381 Distributor.

5 - 8-32 x 0.5" Phillips Screws
1 - Vacuum Line Assembly
1 - Removal Tool

INDEX
FLAT
SPOT

INDEX

CAMSHAFT

Before removing the distributor it is recommended to mark the location of the rotor. This is to ensure
that the distributor and cam are indexed correctly prior to reassembly.

Be sure that the O-ring between the distributor cap and the housing is in place before installing the
cap. The O-ring must be stretched out, then installed onto the housing. It will shrink back to size.

TIMING INFORMATION

Since the timing of the MSD Pro-Billet Distributor can be adjusted, it is recommended that a timing indicator
and mark be fabricated prior to installing the distributor. This way, the timing can be recorded so the MSD
Distributor can be set to the same amount. From the factory,
the MSD Distributor is set to the OEM specs (one and a half
turns).

The MSD Distributor can alter the timing +/-6°, with a quar­ter turn equalling 1° of timing. The adjusting screw has a soft
Loctite compound applied to it for a seal (Figure 2). Repeated
adjustments may loosen the screw. If this occurs, remove the
screw and apply Blue Loctite® to the threads. The screw can
safely be removed from the distributor.

Too much advance may cause detonation resulting in the

TIMING
ADJUSTER

ECU retarding the timing through the engine’s knock sensor.

When adjusting the timing, take note that the ECU varies
the timing at an idle. It is recommended to bring the engine
rpm up to 1,500 - 2,000 when setting the timing.

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 2 Adjusting the Timing.

2 INSTALLATION INSTRUCTIONS

DISASSEMBLY

1. Disconnect the negative battery cable.

2. Locate the radiator petcock and drain the coolant from
the system.

3. Disconnect the MAF, IAC, ICT and TPS sensors (Figure

3). Remove the air intake ducktwork.

4. Once the coolant is drained, remove the upper radiator
hose from the thermostat housing.

5. Loosen the three bolts that secure the crankshaft
pulley/hub assembly. Do not remove them entirely at
this time.

6. Remove the accessory drive belt by moving the spring
loaded idler pulley. Use caution as this pulley is spring
loaded! The belt will slide off the pulley system and the
idler pulley will settle beyond its installed position.

7. Once the belt is removed, proceed with removing the
pulley from the crankshaft hub by pulling the three
retaining bolts. A puller will be required (Figure 4).

8. It may be necessary to remove the cooling fan. This is
done by removing the four bolts and disconnecting the
wiring connection.

9. Disconnect the air pump power wires and remove the
air pump from its mounting brackets.

10. Disconnect the coolant temperature wiring sensor
located on the water pump.

11. Loosen the lower radiator hose clamp and the two
heater hose clamps at the water pump. Coolant will
generally still pour out of the hoses and water pump.

12. To remove the water pump, the power steering pump
may need to be removed. With a short extension, the
water pump bolt should be able to be accessed. There
are six water pump bolts. Once again, more coolant
may spill out.

13. At this point, you should be able to access the distributor
cap! Mark the location of each spark plug wire before
removing them.

14. Remove the vacuum lines (if equipped) and the
distributor connector at the distributor and on the
passenger side of the intake manifold (Figure 5).

15. Using the supplied special tool and a 1/4" wrench,

Figure 3 Disconnect TPS and IAC.

Figure 4 Removing the Hub.

Figure 5 Disconnect the Distributor Connector.

TPS

IAC

MARK ROTOR
LOCATION

Figure 6 Removing the Original Cap.

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 7 Rotor Location.