DWELL ANGLE ADJUSTMENT

The dwell angle or cam angle is the number of degrees that the distributor cam rotates while the points are closed. There is an inverse relationship between dwell angle and point gap. Increasing the point gap will decrease the dwell angle and vice versa. Checking the dwell angle with a meter is a far more accurate method of measuring point opening than the feeler gauge method.

Except 1979 RX-7

1. Start the engine and run it at idle speed, until it reaches normal operating temperature.

   CAUTION
   NEVER run the engine in an unventilated area such as a closed garage. Make sure the doors are open and there is adequate airflow. If possible use fans to provide additional air.

2. Connect a dwell meter to the ignition coil as described in the tool manufacturer's instructions. Read the dwell and compare the reading to the figure shown in the Tune-Up Specifications charts in this section.
3. If dwell is incorrect, stop the engine, remove the distributor cap and rotor, then adjust the point gap as previously described. If the dwell reading is too high, open the point gap slightly; if the dwell reading is too low, close the point gap slightly.
4. After contact point adjustment, replace the cap and rotor, start the engine, then read the dwell again. Readjust as necessary.

1979 RX-7

NOTE: The method of dwell angle adjustment described here requires that some of the high tension wiring be re-routed to permit the engine to run with the distributor cap and rotor off. While this re-routing process requires some extra time, the dwell adjustment may be made with the engine running, which will save considerable time and make it possible for the dwell to be brought to specification on the first adjustment.

1. Start and run the engine until hot, then turn the engine OFF.
2. Note their locations, then disconnect the high tension leads at the leading and trailing ignition coils.

   Fig. 1: Temporarily re-route the high tension (secondary) wiring to adjust dwell with the engine running — 1979 RX-7

3. Note its location in the distributor cap, then disconnect the leading spark plug wire for the front rotor (L1) at the cap. Connect it to the tower of the leading ignition coil.
4. Note its location in the distributor cap, then disconnect the leading spark plug wire for the rear rotor (L2) at the cap. Connect it to the tower of the trailing ignition coil.
5. Remove the distributor cap and rotor.
6. The plug wires for the top two plugs may still be connected to the distributor cap, but the bottom two plugs must be wired directly to the ignition coils as shown.
7. Connect the dwell angle tester to the trailing ignition coil. Then, start the engine and read the dwell. If incorrect, loosen the set screw for the trailing contact set only slightly (or the engine will stop). Then, very gradually move the stationary contact back and forth until dwell is within the specified range (55–61 degrees).
8. When dwell is correct, tighten the set screw and recheck dwell. Readjust it as necessary.
9. Connect the dwell meter to the leading ignition coil and repeat steps 7 and 8 for the leading contact set.
10. Reconnect all wiring, then reinstall the cap and rotor.