Vacuum pressure

[79gmc15]

What kind of pressure should I be expecting from my motor? 1986(?) From a van 305, stock pistons/ heads, comp 268 he cam, sp2p intake, q jet. Idle is set by ear but close to 700 rpm. Timing is set by sound/ping/vacuum gauge. The timing tab and balancer dont match up.

Thanks!

[Fairlane514]

Your timing mark is probably at the 12 O'Clock position on the 305.  Stock should be around 17-19 inches of vacuum. I have about 17 on my stock Goodwrench 350. I'm guessing with that cam probably around 15 inches.