I was wondering what is this or the purpose of that " black drum like thing " on the firewall, beside the underhood light behind the dual snorkel air cleaner ? Thanks
If I have it correctly, that should be the vacuum resovoire? For vacuum controlled items such as the a/c-heater and cruise, if need be. It should have a small hose going to it from a vac source at the intake manifold. (Thanks to Mark for showing me how to enlarge pictures, I feel important!!)
vacuum reservior, stores vacuum for instances of low engine vacuum(wot/climbing hills), keeps the hvac from defaulting to defrost mode when vac is low.
It likely has 2 hoses going to it, with one of them having a one way valve so that when the engine vacuum drops it doesn't lose the vacuum but keeps it supplied to the source as mentioned (defroster, cruise or whatever.)
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
It might only need one line. It stores just store vacuum like as air compressor reservoir stores pressure.
It could also have a check valve in it to prevent it losing vacuum when manifold vacuum drops. In that case, I'd expect it have one line connected to manifold (with a check valve in it) and a second line going to whatever system requires the vacuum.