PRESTOLITE Electronic BREAKERLESS Ignition: Testing

To check bushing wear, secure distributor in a vise and remove rotor and dielectric shield. Attach a dial indicator to housing with indicator plunger resting against trigger wheel. Secure wire loops as shown. See Fig 1 . If movement exceeds 0.006", replace distributor shaft bushings.

Fig 1: Shaft & Bearing Wear Test
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With distributor mounted on a test stand, operate distributor at 300 RPM with a 12-13 volt input. Dwell reading should be 28-34 degrees for 4-cylinder or 26-32 degrees for V8 engines.
The trigger wheel tooth accuracy must be within ± 2 degrees at 45 degree intervals on V8 engines or at 90 degree intervals on 4-cylinder engines. If variance is beyond this limit, check trigger wheel for burrs. Check for worn bushings.
Centrifugal and vacuum spark advance work in conjunction with each other to provide optimum performance. If performance does not meet specifications, check for sticking flyweights, binding trigger wheel, sticking vacuum diaphragm assembly or bad vacuum hose.
Primary voltage tests require sensor coil to be between two trigger wheel teeth. Connect voltmeter between coil negative (-) terminal and ground. With ignition switch on, observe voltage. A reading of 5-8 volts is normal. A reading of 12-13 volts indicates defective ECU or ground circuit. A reading of 0-5 volts indicates a defective ECU or coil.