Having a little trouble understanding manifold vacuum and what affects it. When I start my car the vacuum as measured from a port directly into the intake manifold is low, around 14 in Hg. As the car warms up and the choke opens the vacuum reading gradually improves to around 17 in Hg.
I suspected a leak around the carb or the manifold to cylinder head. In fact found one loose bolt....wasn't it. Used map gas to try to find a leak but couldn't find one. I noticed that the timing was retarded about 2 degrees from spec of 18BTDC at 1400 RPM. Also, I believe the air fuel mixture is a little rich. All hoses where replaced and the vacuum measured with all vac ports on the carb closed in turn.
My question for a good mechanic is will retarded timing and/or a rich fuel mixture have an effect on manifold vacuum?
Thanks for your help.
Sincerely, Tich.