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Vacuum Advance Mechanism

  1. Set engine speed at 2500 RPM. Check for advance by disconnecting and connecting distributor vacuum hose.
  2. If available, connect a vacuum pump after removing distributor vacuum hose. Run engine at idle and slowly apply vacuum pressure to check for advance.
  3. If advance is excessive, check for deteriorated or sagging vacuum controller. If advance is insufficient or there is no advance, breaker plate is not operating properly or vacuum diaphragm is damaged.
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