Vacuum Delay Valve
- Remove air cleaner. Disconnect vacuum line from distributor and connect to intake manifold fitting.
Vacuum should drop by 11.8 in. Hg in 4-6 seconds.
- Remove vacuum line from carburetor (thermo valve) side of vacuum delay valve. Attach a vacuum gauge and 30cc vacuum reservoir to line. See Fig. 2. Start engine, run at idle and check vacuum reading.
- Disconnect vacuum line from intake manifold fitting. Note time required for vacuum reading to decrease by 11.8 in. Hg from idle vacuum. This should take 4-6 seconds. If system does not respond properly, replace delay valve and reconnect vacuum lines.