Quote:

Displacement matters a lot. On a 496 with [Email]243@.050[/Email] cam, 108 CL (not vacuum friendly) I get 13" at idle. Just enough vacuum for PB to work without noticeable issues and assist devices in my book. That's after tuning. Before it was under 10". Increasing initial advance to 20 degrees and tuning idle mixture helped a lot.



I agree. I have a 417 stroker SB with a 242@.050 108 lsa cam and I get 14" of vacuum at idle and my PB work with no issues. As was stated above this was after some idle mixture tuning. My initial advance is at 18 degrees.

It all really depends on your setup.

70 Cuda 340 4 speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350