Manifold Vacuum Advance what am I not getting?

Newbomb Turk said
Ok, that’s another rule of thumb as far as T slot exposure.

I start with a square slot and then open the throttle to get it to idle.

Once I finalize everything I verify the T slots are not open so far that the mixture screws don’t work.

There is no tuning magic in T slot exposure. They can’t be open so far the mixture screws don’t work but they don’t need to be damn near shut to work properly either.

Edit: if you end up with the throttle blades too far open and mixture screws don’t work, we do t just grab the vacuum hose and hook it to manifold vacuum.

I drill holes in the throttle blades so they shut further and correct T slot exposure.

Resorting to MVA to get one to idle is my last resort.

Because in the end, most time guys end up right where you are. It’s not a fun place for sure.

I just solved an idle issue with my son's truck. One of the primary throttle blades was bent exposing too much t-slot on that barrel. He drives it to work all year, and I suspect he may have had a lean backfire last winter. I initially set the carb up 4 years ago, so I did not expect it to be a t- slot problem.