Throttle Advance Schedule Test (1976-77 Dual Pick-Up Distributor Models)

Ensure that throttle position transducer is properly adjusted. Turn ignition off. Disconnect 4-pin connector from Spark Control Computer. With ohmmeter, measure resistance between terminals No. 9 and 10 of 4-pin connector. If reading is 50-90 ohms, reconnect computer and go step 3.
If reading is incorrect, remove connector from throttle position transducer and measure resistance at transducer terminals. If resistance is now 50-90 ohms, an open, short or poor connection exists between transducer and terminals No. 9 and 10. If resistance is incorrect, replace transducer and go to next step.
Reconnect all wires and turn ignition on. Connect voltmeter negative lead to ground, and positive lead to each transducer terminal. Fully open and close throttle. A 2 volt change should occur with throttle action.
Position throttle linkage on fast idle cam and ground carburetor switch with jumper wire. Disconnect wiring harness connector from throttle position transducer, and connect it to known good transducer (for testing purposes).

Move transducer core in until fully bottomed. Start engine, wait 90 seconds, then pull transducer core slowly out to about one inch. See Fig 1.

Fig 1: Actuating Throttle Position Transducer

Courtesy of CHRYSLER GROUP, LLC

1977 SPARK ADVANCE SCHEDULE SPECIFICATIONS

Test Name

⁽¹⁾ Additional Advance (Degrees BTDC or Inches Hg)

Start Timer Advance

318"

All Others

5-9

Throttle Advance (Transducer Out 1 Inch At 75°)⁽²⁾

318"

8-12

440"

California

4-8

Federal

3-5

All Others

3-6

Transducer Core Moved Rapidly In And Out

318"

8-12

440"

California

Federal

All Others

Vacuum Advance (Operating Vacuum Range)⁽³⁾

318"

⁽⁴⁾ 13-15

360"

6-8

440"

None

All Others

3-5

Accumulation Time Advance (After 7-8 Min.)

318"

32-36

440"

California

Federal

All Others

Speed Advance (At 2000 RPM)

318"

⁽⁵⁾ 1-3

360"

2-4

440"

California

5-7

Federal

7-9

All Others

3-5

⁽¹⁾	Additional advance does not include initial ignition timing.

⁽²⁾	On models without air temperature sensor set to 10°BTDC. Disregard specifications on Spark Control Computer that has a Red dot on case, no air temperature sensor is used.

⁽³⁾	Operating range is 0-14" Hg on 318" engine. Operating range is 12" Hg on 440" engine.

⁽⁴⁾	No advance on 318" engine equipped with 4091468 Spark Control Computer.

⁽⁵⁾	At 4000 RPM, advance should be 3-7 degrees.

Adjust timing light so initial timing is seen at timing plate. Meter on timing light should show additional amount of advance as indicated under specifications.
If timing is within specifications, move core back into transducer. Timing should return to initial timing setting. If so, go to next step. If timing did not react as indicated, replace Spark Control Computer. Repeat procedure starting at step 3. If vehicle fails test, replace transducer.
Return timing light advance meter to zero. Observe timing marks while having an assistant rapidly move core of test throttle position transducer in and out 1 inch (5-6 times).
Timing should advance as specified for about 1 second, then return to zero. If advance is not as specified, replace Spark Control Computer. Repeat test starting at step 3, using original transducer. If test fails, replace original transducer.