Can't get it to idle right! (Part 2)
Also where are you measuring manifold vacuum? Needs to be under the carb throttle blades, you said 12 inches at idle and 22 revving it up? Your vacuum should drop as you rev up the engine.
GTS
this is only true of very small camshafts.Like factory teener cams, or slantys.
All performance cams I have tuned (under 250*@050), will idle with low vacuum(the bigger the cam,the lower the idle vacuum) and increase as rpm goes up. Depending on the size of the cam, they will vacuum peak from 1500 to around 2400, or perhaps a little higher.
The spark-port will follow this almost exactly, being a little sluggish at the start, but usually catching up by 1500ish.
This lowest rpm at which the vacuum peaks is the lowest rpm that the engine first becomes efficient. Reversion in the intake has stopped and the fuel-charge is finally being trapped in the cylinder.
From here the vacuum peak usually hangs on another 1000rpm or so (no-load/neutral), before beginning a long slow decline.
For best fuel mileage, I gear the car to run at or a little higher than this vacuum peak.Then if I have to,or as may be desired,I modify the spark-port to pull the Vcan all in, at that cruise rpm.