Mercury 305 CID, Service Manual, Page: 331 / 967

4B-22 - THUNDERBOLT IV AND V IGNITION SYSTEM 90-823225--1 1096
INSTALLATION OF KNOCK SENSOR
IMPORTANT: If installing a new knock sensor, be
sure to replace it with an identical part. Knock
sensors are very sensitive and designed for each
specific application.
IMPORTANT: It is very important that the knock
sensor be torqued to the exact specification. In-
correct torquing will result in unsatisfactory per-
formance. DO NOT use sealer on threads.
1. Install knock sensor in engine block. Torque to
12-16 lb. ft. (16.3-21.7 N·m).
73756
a
a - Knock Sensor
2. Connect electrical connector to knock sensor.
Spark Plugs
1. Inspect each plug individually for badly worn
electrodes, glazed, broken or blistered porcelain
and replace where necessary.
2. Inspect each spark plug for make and heat range.
All plugs must be the same make and number
and heat range. Refer to “Specifications” for
spark plug numbers.
3. Adjust spark plug gaps with a round feeler gauge.
Refer to “Specifications” for proper spark plug
gap.
72734
b
c
d
a
e
f
a - Porcelain Insulator
b - Insulator Cracks Often At This Point
c - Shell
d - Proper Gap
e - Side Electrode (Bend To Adjust Gap)
f - Center Electrode (File When Adjusting Gap - DO NOT
Bend)
4. Clean spark plug seating area. Do not use gas-
kets on taper seat plugs. Install spark plugs and
torque to specifications. Where used, gasket
must be fully compressed to complete heat trans-
fer and provide a gas- tight seal in cylinder. For
this reason, as well as the necessity of maintain-
ing correct plug gap, correct torque is very impor-
tant during installation.
IMPORTANT: Tapered seat spark plugs are not in-
terchangeable with non-tapered (with gasket)
spark plugs.