ADJUSTMENT
4 and 6 Cylinder Engines
Fig. Fig. 1 Contact point alignment
Fig. Fig. 2 Adjustment of the dwell angle (contact point opening)-4 and 6-cylinder engines
If the contact points have been installed and gapped correctly, the dwell angle should be within specifications.
- Connect the dwell meter leads to the distributor terminal of the coil and ground.
- Start the engine and run it at idle speed.
- Note the dwell meter reading. If it is not within specifications, the point gap may be incorrect or the movable contact arm may be distorted. Readjust the contact points and recheck the dwell. Be sure that the correct point set has been installed.
Dwell and point gap must both be within their specification limits at the same time. If this cannot be accomplished, probably the wrong contacts are installed, the rubbing block or cam lobes are badly worn, or the movable contact is distorted. A dwell variation test (see below) may be performed.
8 Cylinder Engines
Fig. Fig. 3 On 8-cylinder engines, adjust the dwell angle using the proper sized hex wrench
Because the contact points are preset, it is not necessary to gap them with a feeler gauge. The dwell angle can be adjusted by turning the adjusting screw located behind the small window of the distributor cap.
- Disconnect and plug the vacuum line from the distributor.
- Connect the dwell meter leads to the distributor terminal of the coil and ground.
- Start the engine and run it at idle speed.
- Note the dwell meter reading. If it is not within specifications, raise the window of the distributor cap and insert the proper size hex wrench in the adjusting screw head. Observe the dwell meter and turn the adjusting screw until the dwell angle is within specifications.
DWELL VARIATION TEST
Excessive wear of the distributor mechanical parts may cause variations in dwell that affect ignition timing. The following is the procedure for a dwell variation test.
- Disconnect the vacuum line at the distributor, connect the dwell meter, and run the engine at its idle speed.
- Slowly increase engine speed to 1,500 rpm and then slowly reduce to idle speed while noting the dwell meter reading.
If the dwell reading varies more than two degrees, wear in the distributor shaft, bushings, or breaker plate is probably excessive. The distributor will have to be removed for a complete inspection and test.
Dwell variation at speeds above 1,500 rpm does not necessarily indicate distributor wear.
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