How many inches vac. should I get from my 383, CC XE274H, Vortec heads, 700DP and Perfromer RPM. What initial timing would be a good starting point?
I have it set at 10 BTDC now, with a best of 13" vacuum when adjusting carb.
Thanks,
Guy

13" sounds about right for that cam.
As for timing - let the initial fall where it may and set your total around 35, thats a good ball park # (35) to start with. The initial will depand on how much advance your distributor has built in to it, if its a performance HEI type, they have around 15deg of adv. built in, so initial would be 20 and total would be (15 more) 35deg. Thats what I run on my 383 - 20initial, 35 total.