Vacuum Tuning

New Quickfuel carb installed and now starting to do tuning.

Engine

340 X heads ported by Justin AKA Wild and Crazy.

Stock manifold but we are going to be putting on a LD340

Stock exhaust manifolds

Cam is an ISKY 777 650-750 CFM Carb. 10.5:1 compr. RPM-Range (3000-7000) Valve Lift (.480 .480) Valve Lash hot (.018 .018) ADV Duration (280 280) .050 Duration (240 240) LC 108

Carb is SS 680 with vacuum secondaries.


Here is my primary question.

Do you connect PCV valve for intial vacuum testing? The reason I ask is because so far I am seeing 10 to 12 inches at idle, and it bounces quite rapidly. If I block the PCV valve the idle will drop and the vacuum will drop to a fairly steady 10 inches. Is PCV valve supposed to allow pretty much open vacuum? Am I seeing such low vacuum at idle due to cam? If I open the throttle to say 2500 RPM the vacuum jumps way up to 30 inches or so. Quick blip causes a quick drop as expected.

Idle is pretty clean at this point with very mild lope. And exhaulst is no longer such an eye burner. Four corner idle is responding well, however I am gettting increase of vacuum failry deep into settings. Say 3/4 out. So I still may be a bit rich on the idle circuit.

Thx

Spinman