timing jumpy with manifold vacuum hooked up.

[steveo3318]

I have read TONS of info on timing and finally have my 383 about dialed in where I want it. But I have a very simple question. Can the size of a cam make the vacuum jumpy and make timing jump a little at idle?

My timing is smooth as a button with manifold vacuum unhooked at idle. But hook it up and it goes up about 8 degrees "as it should" but it jumps a little almost with the lope of the cam when I hook up the vacuum. Is this jump ok? It might be a deg. or two max.

383 11.1 compression, 67 cc world heads, 308/296 510/510 roller cam. If any more info is needed please let me know. I just don't like seeing it jump a little on the light!!!