Absence of front pump pressures results in no drive i any range as this pressure is required to apply the al plicable clutch for a given range Common causes woul be stuck pressure regulator valve broken or disengage front pump shaft or missing plug from front end of froi pump shaft which would divert converter in Moderately low front pump pressures in all range would indicate a restricted front pump in Failure of pressure to rise when disconnecting th vacuum hose or high pressures with the hose connecte4 would indicate a stuck vacuum modulator valve defectiv vacuum modulator or collapsed hose Rear Pump Check With the rear wheels raised place the selector in D and accelerate the engine Front pump pressure show drop to approximately 0 5 psi at approximately 20 MPF If pressure does not drop rear pump is disengaged c clogged or rear pump check ball not seating THROTTLE VALVE TV PRESSURES PSI Condition R N D L Disconnect TV rod at carburetor and vacuum hose at balance tube Depress 0 0 45 47 84 105 accelerator to W O T By disconnecting TV rod at carburetor engine remair at idle speed throughout test n Throttle valve pressure tests are of value in cases where the transmission shift points are not in accordance d with the Shift Point MPH Chart If pressures are not d as prescribed they may be raised or lowered by ad it justing the position of the jam nut on the throttle valve assembly fig 7E il To raise TV pressure 3 psi back off the jam nut one 1 full turn This increases the s dimension from the jam nut to the throttle valve assembly stop Conversely tightening the jam nut one 1 full turn e lowers TV pressure 3 psi Smaller pressure adjustments l can be made by partial turns of the jam nut The end of e TV adjusting screw has an Allen head so the screw may be held stationary while the jam nut is moved CORVAIR POWERGLIDE SHIFT POINT MPH CHART Axle 3 27 3 55 r Upshifts MPH Minimum Throttle 14 18 12 15 Full Throttle 48 52 42 48 Part Throttle Detent Touch 35 44 33 40 Downshifts Closed Throttle 12 15 11 14 Full Throttle 42 48 38 44 Part Throttle Detent Touch 24 33 22 30 Matrual Low Inhibited 56 81 52 57