According to my service manual, the engine on my '72 is supposed to have this distributor vacuum control switch(also called thermal vacuum switch, or TVS) It has three vacuum ports on the side, and one on top along with a 2 blade electrical terminal. I have something like that in the front of the intake manifold, to the left of the thermostat housing, but it does not have the top port or electrical connection.This looks like the only place where this switch could be located. Does this sound like a similar switch but maybe from a different year or car? Right now my distributor vacuum line is hooked directly to manifold vacuum, which does not really matter right now since the car is not being driven.(electrical problems). I would like everything to be there as original and functioning. Also that big diaphram on the side of the intake. Is that part of EGR (exhaust gas recirculation)? The vacuum hose for that is connected to one of the 3 ports on the switch I described. Any resources for detailed pictures of these components? Thanks, Chumley

 

This is a Transmission Control Switch http://i122.photobucket.com/albums/o...trolSwitch.jpg

And the arrow here shows it installed http://i122.photobucket.com/albums/o...0cruiseTCS.jpg

Is the big diaphragm in the foreground of the second picture the one that you mean?

C.J.

 

Yes, this is the part shown in the manual and is located in the same place where the unit I described that I have is. The large diaphram I described is on the driver side and is about midway in the intake manifold. I'm starting to wonder if this engine is original to the car. Haven't got the engine unit number off the block yet, I misplaced my inspection mirror. Also seems that the A/C may be aftermarket as well, at least the compressor is a remanufactured unit. Another enigma.......

 

Can you post some photos for us? A diaphram kinda thingy half way along the intake sounds like a later 70's smog fitting. The switch with vacuum hoses C.J. showed you should be correct for your year. If yours also has a vacuum port in the top that also may be something from a different year.

C.J. is that your engine? I'd heard the cruise control for this vintage is hard to make work smoothly. I've got all the parts for my 1971 Cutlass Wagon but haven't hooked it up yet. Wasn't sure it would be worth the trouble. John

 

Not my motor, unfortunately. It's just a really clean 72 (I think) W-30. I have cruise in my Cutlass....but it's not hooked up (yet!). It will be after my 455 swap and then....let the troubleshooting begin!

C.J.

 

I will try to post some pics later today of what I have. Is it possible to post pix directly to the threads on this site, or does it always just post a link? I suspect the diaphram on the side of the manifold is related to EGR, which as far as I know was not used on '72 engines. Hence, my suspicion that this may not be the original motor. Does any vendor carry the TVS? I saw a NOS one on ebay and the seller claimed they are not produced anymore. Also can I just run my vacuum advance directly to manifold? (I have HEI)

Chumley

 

Chumley,

Open a free ccount at Photobucket,upload, and link to them.

C.J.

 

Here are a couple of pix, one is of the vacuum switch just to the left of the oil fill tube, and the other of the EGR valve.