Holley 600 vacuum issue cannot figure out.

[gpoetx]

327 SBC with a 1850 600 Holley. No Vacuum on the Metering block at idle and the car idles with the Idle screws all the way in, throttle screw all the way out and adjusted Floats. Currently had a 6.5 power valve and 65 jets. Also has a pretty mild RV Cam. Also has no Vacuum issues at the Throttle body. Very rich, in my garage, so gets hard to breath in there even with the door open. Any help greatly appreciated.

[Gaz64]

Where is the engine getting the air from? I'd check the secondary throttle shaft is returning to the throttle stop, and not sticking partly open. If you're using a thick base gasket, then the throttle body can warp enough for the secondary shaft to bind. And you don't get vacuum on the metering block until some time after the primary side exposes the ported vacuum takeoff in the throttle body. That nipple is ported vacuum, not manifold vacuum. Gary