Rick, if the vacuum goes from 18 to 12, that does not sound like the cam. What kind of rpm drop do you get going from neutral to in-gear? I did not understand your comment about the initial timing. One thing to look for with your timing: be sure that the mechanical advance is not partially coming-in when idling in neutral. If you have some mechanical advance in when in neutral, you will lose some or all of it when you put it in gear, causing a large difference in neutral to in-gear idle quality. I have not run that cam but have run others that, on paper, are larger than that one and had more than 12" vacuum in gear.