Distributor Installation; Engine Not Disturbed; Engine Disturbed; Ignition Timing - MerCruiser GM4 Service Manual

Distributor Installation

Engine Not Disturbed

1. Install new gasket on distributor housing.
2. Turn rotor approximately 1/8 turn in a counter-
clockwise direction
scratched on distributor housing.
3. Work distributor down into position in engine
block with distributor positioned as noted during
removal.
IMPORTANT: It may be necessary to move rotor
slightly to start gear into mesh camshaft gear, but
rotor should line up with mark when distributor is
down in place. Distributor shaft must enter oil
pump shaft for complete installation.
4. Replace and tighten distributor hold-down bolt
and clamp. Connect primary lead to coil. Also
install spark plug and coil secondary wires , if re-
moved.
IMPORTANT: Wires must be installed in supports,
to prevent cross-firing. Firing order is 1-3-4-2.
5. Set points gap to .016 in (0.5 mm).
6. Install rotor
7. Check dwell (39- 45 degrees)
8. Time ignition as outlined under "IGNITION TIM-
ING".

Engine Disturbed

1. Locate No. 1 piston in firing position by either of
two methods described below.
a. Remove No. 1 spark plug and, with finger on
plug hole, crank engine until compression is
felt in No. 1 cylinder. Continue cranking until
pointer lines up with timing mark on crank-
shaft pulley, or
b. Remove rocker cover and crank engine until
No. 1 intake valve closes, continuing to crank
slowly until pointer lines up with timing mark
on crankshaft pulley.
2. Position distributor to opening in block in normal
installed attitude.
Index
4B - 10 - IGNITION SYSTEM
past mark previously
3. Position rotor to point toward front of engine (with
distributor housing held in installed attitude), then
turn rotor counterclockwise
1/8-turn more to the left and push distributor down
to engage camshaft. It may be necessary to ro-
tate rotor slightly until camshaft engagement is
felt.
4. While pressing down firmly on distributor hous-
ing, engage starter a few times to make sure oil
pump shaft is engaged. Install hold-down clamp
and bolt and snug up bolt.
5. Turn distributor body slightly until points just open
and tighten distributor clamp bolt.
6. Place distributor cap in position and check that ro-
tor lines up with terminal for No. 1 spark plug. In-
stall cap.
7. Install cap, distributor primary lead to coil. Check
and connect spark plug wires, if they have been
removed. Wires must be installed in their proper
location in supports to prevent cross-firing. Firing
order is 1-3-4-2.
8. Set points gap to .016 in (0.5 mm).
9. Install rotor
10. Check dwell (39- 45 degrees)
11. Time ignition as outlined under "ignition Timing".

Ignition Timing

1. Connect timing light to No. 1 spark plug. Connect
power supply leads on light to 12 volt battery. Re-
fer to "Specifications" for cylinder numbering and
location.
2. Connect tachometer to engine.
3. Start engine and run at normal idle speed.
4. Aim timing light at timing tab, located on timing
gear cover and crankshaft torsional damper.
approximately
90-816462 2-695