Quote Originally Posted by DogKrapFace View Post
An easy way to cut off vacuum advance is to leave the hose attached to both carb and distributor and use a pair of needlenose pliers to pinch vacuum line when setting timing.
If the hose it left in place, when you pinch the hose, any vacuum in the diaphragm will be trapped and possibly cause an erroneous timing check/adjustment. Always remove & plug the vacuum supply hose to the dizzy.