[BugzC10]

Have you ruled out any leakage between the intake and carb? Are you mounting a square bore carb to a spread bore manifold or visa versa? The reason I ask. I'm also chasing low vacuum and I discovered that the PO installed a square bore to spead bore adapter upside down and that I my vacuum leak may be coming from the missmatch or lack mating surfaces. I ordered a new plate specifically for SQ B to SB configuration. I'll let you know if it cures my vacuum issue.