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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,234
They used to be plugged into vacuum switches that were part of emissions controls. One operated the diverter valves in the air pump system and the other blocked the vacuum retard line to the distributor to advance timing and help raise idle speed a few hundred rpms for a minute or two after a cold start.

The red vacuum line is for vacuum retard and the blue one is vacuum advance/boost retard on the distributor.
The red one looks a little beat up from people wrenching on the 13mm nut below it while adjusting ignition timing. Those vacuum lines are really old now and with the colored fabric over the rubber hose you can't see if they are dry rotted, cracked, or broken underneath and they should be replaced.
Old 01-19-2014, 08:55 PM
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