Section VII. MAINTENANCE OF THE ENGINE

wires as necessary.

4-12. Radio Interference Suppression

Components

a. Primary Suppression Components. The primary

4-14. Testing of Radio Interference Suppression

suppression components are those whose primary

Components

function is to suppress radio interference.

b. Secondary Suppression Components.

These

Test and inspect the spark plugs as outlined in

paragraph 4-37. Test the high resistance carbon ignition

components have radio interference functions which are

wire by connecting an ohmmeter to each end of the

incidental or secondary to their primary functions.

wire. If the meter reads an infinite resistance, the wires

4-13.

Replacement of Suppression Components

have an open or break and should be replaced.

Replace the radio interference suppression components

by replacing the spark plugs or ignition

Section VII. MAINTENANCE OF THE ENGINE

(7) Repeat the same procedure for all six

4-15.

Engine Test and Adjustments

cylinders; each cylinder should be tested the same

a. General. Proper clearance (lash) between rocker

number of compression strokes to assure accurate

arms and end of intake and exhaust valve stems is very

readings.

important. Insufficient valve clearance will cause loss of

(8) Replace all spark plugs and wires in the

compression, misfiring, and will eventually cause

proper positions; replace the high tension lead on the

burning of valves and valve seats. Excessive valve

distributor.

clearance will cause faulty engine operation, valve

tappet noise, and rapid wear on valve operating

c. Adjustment.

mechanism.

(1) Remove rocker arm cover, gasket, and high

b. Compression Testing.

tension wire from ignition coil. Discard the gasket.

(1) Be certain the ignition switch is in the OFF

(2) Starting with number one cylinder, crank

position.

engine with starter motor until both valves are closed

and the push rods are in their lowest position on the

(2) Remove the high tension wire from the center

cam.

of the distributor.

(3) Check the clearance between rocker arms

(3) Remove the spark plug wires, and remove all

and valve stems with a 0.015 inch feeler gage. It should

spark plugs.

pass between the rocker arm and corresponding valve

(4) Put the transmission in NEUTRAL.

stem with a slight amount of drag when valve lash is

properly adjusted.

(5) Insert compression test gage in spark plug

hole.

(4) Adjust each valve by turning the adjusting

screw clockwise to decrease the clearance or

(6) Crank engine for at least four compression

counterclockwise to increase the clearance, as

strokes. Note reading on first full stroke as well as on

necessary. Refer to figure 4-2.

final stroke. Gage should read 125 psi, plus or minus 10

psi between cylinders.

4-9