1979 Models
- Remove air cleaner. Detach vacuum line from distributor. Disconnect air by-pass valve line (Calif, only) or anti-afterburn valve (Federal) at intake manifold fitting. Install vacuum line removed from distributor to intake manifold fitting.
- Remove vacuum line from carburetor side of spark delay valve, plug line and attach vacuum gauge to vacuum delay valve. Start and run engine at idle speed.
- Detach vacuum line from intake manifold fitting. Note time required for vacuum reading to drop to 11.8 in. Hg. This should take 4-6 seconds. If system does not respond as indicated, replace spark delay valve. Reconnect vacuum lines to original positions.
Courtesy of FORD MOTOR CO.