April 25, 201213 yr In preparing to install the intake manifold on ea81, noticed this broken piece. Is it a vacuum valve or something? I have to find a replacement STAT.
April 25, 201213 yr I'm usually pretty good at playing the random part identification game, but this one is a tuffy. I would also like to know what this is! I'm sure someone has one as well. -Tom
April 25, 201213 yr It appears to be a thermal vaccum switch. It looks like the ones GM used during the smogged late carbed models.
April 25, 201213 yr Author EA81 is stamped on the block. I have a single barrel Carter-Weber carb. And the vehicle is front wheel drive.
April 25, 201213 yr It's the "Thermo Vacuum Valve I"... it's used to reroute throttle plate vacuum that normally goes to the distributor, EGR valve, and vapor canister to the air cleaner (ie. the valve modulates the vacuum pressure between manifold levels and atmosphere levels when it's activated). The valve is only activated when the coolant is between a certain temperature range (which I think is something like 58F to 98F)... so, it's pretty much useless, because the amount of time your engine coolant is normally going be in that range is probably between 30 seconds and 2 minutes (depending on ambient temp). I've bypassed it all together on my CA setup EA81. PM me if you want a copy of the pages from the FSM outlining it (if you're super curious and dying to look at vacuum schematics). Edited April 25, 201213 yr by skingry
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