Auto Transmission Shifting Issue Since 4bbl Upgrade

If there is no kickdown on it find a new mechanic. The KD (properly know as throttle valve or TV linkage) does much more than kick down the transmission. It controls internal transmission fluid pressure in relation to throttle setting. This affects shift points. At higher throttle settings the TV linkage sets the transmission fluid pressure higher to increase holding capacity of the clutches and bands.

Basically, at wide open throttle, the TV lever on the transmission should be pushed all the way back. At idle it should be free to return, unencumbered, all the way forward. It should start moving back slightly after throttle tip in, or just off of idle.

Without a TV linkage your transmission will be short lived.