The vacume gauge in my 1966 Cutlass displays zero at idle and then picks up when you open the throttle to around 17, I think it’s using ported vacuume, it’s connected to a point on the carburettor. does anybody know where the correct place to attach the vacume pipe is, did these gauges read from ported vacume or manifold vacume when the car was first built. Any pictures or vac pipe diagrams would help. Thanks

 

You'll want to get a 66 chassis service manual for your car. The gauge should be on manifold vacuum if you want a reading at idle. I don't have the 66 CSM and the moto minder gauge was not issued in 67, so it's not in the one I have in the accessories section. If your car is air conditioned, trace the vacuum line from the can on the firewall back to the engine, you can "T" into it there. There should be a small fitting off the intake manifold that has that, and the distributor advance, back right area of the engine.

 

The vacuum gauge is supposed to be connected to any port that provides straight manifold vacuum. This isn't rocket science. Any port that screws into an intake runner will be equivalent. You can tee into the port that is used for the AT vacuum modulator, for example.