84 5.0 w/carb conv.not cooperating/HELP!

well, with a stock cam, and stock style heads-which are great for that velocity, i'm sure that 570 is nothing short of fantastic for all around performance...not to mention that most of the time vac sec carbs provide better driveability and smoother power curves for hoover inducing low duration cams

also, if out of all the carbs you used, the spark advance port never worked-that would definitely have something to do with off-idle and midrange operation. it's kinda wierd that none of them ever pulled any vacuum though...i've never seen that one, unless it's plugged.

just cking-your vacuum diaphragm in the dizzy is good, right? i've had one go bad before and couldn't figure out why i had a little vac leak, and my get up and go got up and left...easy fix though.

I've had more than one vaccuum advance pot go bad too.

Well the unit is a crane adjustable vacuum advance cannister attached to a 76 granada distributor with vacuum and mechanical advance. Vacuum canister has been sitting for about 3 years now unused so it could have dried out too. Been running 36 degrees total and 14 initial for these same 3 years now.

Holley avengers had misdrilled vacuum advance ports on their early years and my double pumper did not come with a port. Anytime the vacuum advance is hooked up, it will idle but will visciously backfire if any throttle is added....making me think the SP-advance port is hooked to manifold vacuum. It's the port on the metering block.