Manifold Vacuum Experiment

Post #95. Wrong.....again.
GM used MVA on production engines until 1968. Chevs had about 24* at idle, much of that MVA.

My 1966 GTO came with 10.75:1 comp ratio with a very mild '067' cam. 197/212* @ 050 duration. Initial timing was 6* + 20* MVA; so idled at 26*.