TIMING THE MODEL A DISTRIBUTOR

Distributor-Cam Adjustment Simple & Accurate

Timing the Model 'A' ignition by rotation of the distributor cam is a "hit and miss," difficult and inaccurate method. The "lash" in the cam drive mechanism and no cam-degree measurement method are the sources of the problem.

An article, "Ignition Timing the A," in the MODEL A TRADER - Jan/Feb 1992 ¹ issue discussed the theory for optimum timing. It also presented tools and a method for measure of the timing under engine running conditions.

The tools consisted of the crankshaft degree indicator, cutaway distributor cap, and offset cam adjusting wrench shown in Figure 1 of this and the referenced article. A conventional timing/ strobe light, was used to illuminate and measure the actual degree of spark retard /advance while the engine ran. The instructions supplied with the kit also suggested timing settings based upon a large number of cars tested.

Timing change or adjustment by the cam rotation is difficult because there is no absolute reference for the cam-contact points position within the distributor. A cam-contact points degree measurement scale and method to "change/ set" the cam position a KNOWN number of degrees has been developed and tested over the past half year on several cars.

The measuring/ adjusting tool is shown in Fig.2. It is a crankshaft degree scale keyed to the distributor. It shows the cam relative degree position in conjunction with the offset cam wrench of Fig.1. A desired known specific crankshaft timing degree change can now be made, measured and reproduced.

Application first measures the degree of initially set or existing relative crankshaft position. The cam hold-down screw is loosened and the cam rotated the desired advance or retard degrees of change; the screw is then tightened. The cam is always held to remove the ever-present "backlash" during adjustment or rotation during tightening. The timing degree change desired was determined by a "timing light" crankshaft pulley measurement following the instructions accompanying the kit ² of Fig.1.

If a "timing light" is not used, the cam position can be changed a known trial number of degrees. A vehicle road test is next made to determine the engine performance. The need for further change can be determined and KNOWN timing change be made accurately and reproducibly.

¹ Copies of the referenced article, or other articles from past issues of MODEL A TRADER, may be obtained from MODEL A TRADER, 1247 Argonne Road, South Euclid, OH 44121 for $1.00 postage and handling.
² The Timing-Crankshaft Kit and Cam Scale were designed for and are being produced by Nu-Rex, Box 9332, Akron, OH 44805. They are also available from Bratton's Antique Ford Parts, and Snyder's Antique Auto Parts, Inc., 12925 Woodworth Road, New Springfield, OH 44443.

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