I have a 383 with a radical (what I think to be radical) cam, although I do not know the specifics on lift, duration, etc--just that it is a roller with a very "lumpy" idle...
I measured the manifold vacuum (I just rebuilt the carb--Holley 650 DP, so I am now in "tuning mode"), and it is only showing at around 5 inches of vacuum at idle (this is with the initial 1.5 turns on the idle screws as a starting point)...
How do I (do I need to) improve the vacuum at idle? I do not run anything that requires vacuum except for the PCV system, and the vacuum advance on the dizzy.
I should also probably note that I have set the initial timing at 14* BTDC--I do not know "total" timing as my damper is not degreed, but the HEI appears to be stock (but for the ACCEL Super coil)...
406, 10:1, comp xr282HR, Dart Iron Eagle 200cc, Holley Contender dual plane, Holley 750 DP
GM 8.5, 3.73 posi