I was curious if I need to start looking for outliers on troubleshooting my vacuum. I only have 8-9 inches at idle and would have thought to be in the 12 inch range. It's all good, but making tuning a PTA (idle and transition circuit).

Is that what I should expect for vacuum on the below build?

383 SBC 10.96:1 compression
AFR 195 comp ported heads
AFR titan dual plane intake
Holley 750, vacuum secondary
Cam: 236/244 @ .500 / LSA 111/ installed 6 deg advanced

Perhaps posting your setup and cam specs would help me come to a conclusion.

 

I've a 355 with Comp XR 288. 236/242 with the ICL set at 104. CR is about 10.2:1. Idle vacuum is 10" on a worn out shortblock. Cranking compression is down about 20 PSI.
I run a TON of idle ignition advance. 16 static plus another 14 through the vacuum advance. It makes a world.of difference.
What's your idle timing and idle RPM?
FWIW: Comps website claims 9.5" Hg @ 1000 RPM & 12" Hg @ 1200 RPM w/ no load. Seems low to me but not far off from what you have.
Like I said, a big cam will eat up a lot of timing. That will help to close the throttle blades some energy restoring the transition slot to where it should. It also improves the responsiveness of the idle mixture screws and part throttle response.

 

Im super conservative on the timing right now at 7 deg base and limit the vacuum advance to 5 deg. This is due to my near 11:1 compression and 210psi cranking pressure. I currently only have an hour run time on the motor so didn't want to start pinging during initial startup, break in, etc...

I'll bump the timing up to 32 deg total and that should bring me up to 10 or so at idle and see what that does for me. Thank you.

 

That's a very healthy cranking compression. I had a similar build albeit with iron heads. Even so, it would eat up 12-14 static (I ran ported vacuum advance back then) and I can't say there was an issue.
​​​​​​When you say you have your cam advanced 6 degrees are you saying your intake centreline is at 105? Or further still? I'm trying to take into consideration what's likely ground into the cam which is typically 4 degrees.

 

Intake CL of 105 yes. Logic... I wanted to run 236/236, 109lca, 4 deg advanced, 105 centerline. Good heads, good exhaust, however I plan to run nitrous at the track. Keeping the same intake timing and opening the exhaust valve 8 deg earlier gives me a 111lca, 6 deg advanced, keeping the 105 centerline.