The Stovebolt Site Forums The Shop Area Driveline Hydra-Matic Transmission, Dramatic rpm drop when putting in drive

Mario,

If you do not have a GMC Shop Manual, I'll look up the idle speed setting. For a 1954 Chevrolet truck with Hydra-Matic transmission, the idle speed is 400-450 RPM, with shift lever in neutral.

I do not have extensive experience with my Hydra-Matic but I found the shifting pattern (up-shift and down-shift) to be very sensitive to the idle setting and to the adjustment described in the Maintenance & Adjustments Manual.