SECTION I - INTRODUCTION

TM 9-4910-749-10

SECTION I - INTRODUCTION

(2) On GENERAL MOTORS vehicles

using the High Energy ignition (HEI)

1-1. GENERAL INFORMATION

system, instead of connecting the RED

test clip to the negative (-) terminal of the

c o i l , connect ths RED test clip to the tach

a. The Inductive Dwell/Tach is used to test and

adjust dwell, idle speed and idle mixture. It is also

terminal using the HEI terminal adapter

used to test the mechanical wear of the distributor,

clip provided with the tester. The tach

the PCV system and the condition of the breaker-

terminal is Iocated on the distributor for

points and the air-filter.

V8 and V6 engines while it is located on

the coil for 4 cylinder or L6 engines (See

b. The Inductive Dwell/Tach will work on any 4,

Figure 2).

6 , or 8 cylinder, 4 cycle, negative or positive ground

(3) On vehicles with a POSITIVE

engines.

GROUND electrical system, connect the

BLACK test clip to the negative (-) ter-

1-2. ZERO ADJUST

minal of the coil and the RED test clip to

the engine ground.

The pointer on the meter should rest on 0 whenever

the leads are disconnected from the engine. The zero

adjust lever is in the front. To zero the meter, move

the zero adjust lever to the right or left until the

pointer lines up on 0.

CAUTION

Read and observe the Safety Rules and

Warnings for Automotive Maintenance in

the front of this manual BEFORE PRO-

FIGURE 2 - HEI IGNITION SYSTEMS

CEEDING.

SECTION II - OPERATION

1-4. POINT RESISTANCE TEST

1-3. BASIC TEST CONNECTIONS

Perform this test if y O U h a v e h a r d s t a r t i n g , i n a c c u r -

ate timing, a rough running engine and poor fuel

a. T u r n t h e C Y L I N D E R s e l e c t o r

the

appro-

economy which can be caused by burned points.

priate position for your engine.

a. Turn the test selector to the POINT RESIS-

b. Connect the RED test clip to the negative (-)

TANCE position (See Figure 3).

terminal of the coil and connect the BLACK test

clip to the engine ground (See Figure 1).

b. Turn the cylinder selector to the 4 cylinder

position.

c. Turn the vehicIes IGNITION SWITCH to the

ON position.

FIGURE 1 - BASIC TEST CONNECTIONS

NOTE

FIGURE 3 - TEST SELECTOR AT POINT RESIS-

(1) The negative (-) terminal of the coil

TANCE POSITION

on FORD vehicles is marked DEC.

1-1