System Testing
- Connect a vacuum gauge to distributor main diaphragm hose and another to distributor sub-diaphragm hose. See Fig 1. If equipped with high altitude compensation system (HAC), disconnect lower HAC vacuum hose and reconnect to intake manifold.
- Warm engine to operating temperature. Pinch hose between vacuum pipe and vacuum transmitting valve (VTV). Increase engine speed to 2500 RPM and release hose. Vacuum gauge should indicate high vacuum within 2-5 seconds after releasing hose.
- Remove hose from VTV on vacuum pipe side. Vacuum gauge reading should drop rapidly to zero. Remove vacuum gauge and reconnect hoses.
- Remove distributor cap and rotor. Apply vacuum to diaphragms and verify vacuum advance moves. Reinstall rotor and cap. If system performed as described, it is okay.
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