[PGSigns]

When you are verifying time you need a timing tape or a timing light with adjustability. To see what it has mechanically cap the vacuum advance and see what the timing is at idle, raise the rpm up 500 and check it again. Do this till you get all in on the mechanical advance. This will give you your timing curve. You have to have this to see what it up and also to see what you get when you put a kit in one or swap a new one in. I use a hand held vacuum pump to test what is in a distributor for vacuum advance. I let the engine idle and increase the vacuum a couple of inches at a time till I get full advance and plot the curve. This lets you know not only the true amount of advance but when it will be in. This allows you to adjust the vacuum advance to your engine combination. A drive with a vacuum gauge hooked to the port you are using will tell you the range you are working in to help choose the correct pot.
Jimmy