Cam Change

[burnin oil]

Whats the base timing at idle? That is not a big cam at all and should have no vacuum issues. I have 250 duration cam in my truck and still have vacuum brakes that work. It sounds like you need a recurve of the distributer. I would hook the vac gauge back up and twist it to you get a good vac reading then limit the advance to the 32 degrees you want overall. Once the curve is set you can play with the vac advance if you like. I dont have it hooked up on my truck and milage is horrible. 7.5mpg on a good tank! I am willing to bet that it will run better with vacuum advance when the curve is set up correctly and gain a little mpg as well. I would not listen to GM here unless it is a track only vehicle. They are not always correct.