Secondary Actuators, Upside down or Not

[A26B]

Ideally, if the actuator arm was a rod, connected straight through the center of the diaphram and perfectly aligned with the linkage bellcrank, then there would be no controversy, but it's not.

As it is, the actuator arm is an "L" bar and the linkage arm is offset from its connection at the center of the diaphram. when the actuator arm is aligned with the bellcrank, the center of the actuator diaphram is not aligned. As such, the pull is angular when vacuum is applied to the actuator.

As Bearly Flying observed, when the arm is "angled" to the bellcrank, the center of the actuator diaphram is in alignment and the pull is straight when vacuum is applied to the actuator.

When the actuator is installed with the linkage arm "straight," you can see the diaphram move angular in the housing as vacuum is applied. This is evidenced by the need to grind & remove metal from the arm to clear the actuator housing when vacuum is applied.

Scott, Your analysis would be correct IF the linkage arm fitment to the bellcrank shaft was such that it forced the arm to remain perpendicular to the bellcrank attachment pin. It is not however, as it fits loosely enough that it works more like a flexible ball chain than a connecting rod.

On my 60K mile 94, I tested the actuators as they were installed "angular" and reversed "straight." "Angular" operated smoothly and quickly, "straight" was jerky & took slightly more vacuum to open fully.

I consider Gorden Killebrew a good friend and a true genius on the C4 Corvette from bumper to bumper, but he was responsible for propagating the "installed backwards at the factory" myth. He is incorrect in this assumption.

The angular linkage arm does look "wrong" but in reality it is not installed upside down and it works perfectly in that configuration. Most importantly, it was purposely designed & installed that way.