Switch pitch

[Mikel]

Hello,
If I'm going on the highway at 2500 RPM and the switch pitch TC goes to high stall under heavy throttle, would I see an RPM increase or does the slippage go away at higher RPMs?
Thanks.

[69W34]

Mikel, this may help ... the SP converter is driven (activated) by the large switch at the rear of the motor, it is connected to the carb with a rod, which it in turn moves the bell crank on the switch as you press on the accelerator. There is an electrical plug/wires that down into the transmission to two solenoids on the valve body. Depending on how hard you accelerate the switch will engage a given solenoid altering the fluids path way in valve body that controls the stator closing the vanes in the converter thus allowing the engine to wind up the RPMs to 2800 or so before it stalls (while standing still or getting under way). This of course brings the motor well into its torque/HP curve for launch.
When cruising at 2500 RPMs you’ve already locked up @ what ever the low stall RPMs are 1000-1800, stand on the throttle and you’ll triggering the switch/converter into high stall - 2800 so, you’ll get a bump in RPMs until you reach the 2800 threshold at which point it effectively ‘stalls’. Keep in mind when you stab the throttle you’re liable to kick down the transmission as well thus upping the RPMs, secondary’s (if equipped) will open and given final drive you should be going places fast.
This is a bit simplistic but you get the idea, there are some very good articles on line under (Switch Pitch)

Personal note GM had a good deal going with the SP converters had they retained it they would have had a leg up on the competition in the performance and fuel mileage. But then there were some things the general did that made no sense!