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should I unplug the pcv valve to use for my vacuum guage?
Not sure what you mean by unplug the PCV valve, but leave it in the normal operating configuration. When you check vacuum or use vacuum on accessories you want normal vacuum, meaning PVC valve operating normally. Speaking of PVC valves, I actually had one go bad recently. Over a period of 2 months the idle speed kept climbing and the computer couldn't keep it down. Decide to check for vacuum leaks and when I put my thumb over the PVC valve inlet the idle dropped to 550rpms. That's only the second bad one I have ever seen. It even rattled like they tell you to check them.
I have been unplugging the vacuum going to the pvc and using it for my gauge.
That gives you a false reading as the PVC bleeds some air into the intake to operate properly. Teeing into the line is ok but a better place is off one of the nipples on the base of the carb or off a manifold nipple or even off the vacuum tree on the firewall where most vavuum accessories come off of. The vacuum signal in the PVC line, if you tee into it will be slightly low is all.
I plugged the gauge into the base of the carb and set the timing to 8 degrees.
I also adjusted the idle air mixture with the gauge and the needle is almost steady.
How much should it move?
The one problem with the perscribed method is it doent take into account repacement camshafts....Anything over stock will start to drop manifold vacuum...somtimes near 1-3 inches with a radical cam...Or increased vacuum with a worn cam...
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