Locate TDC on the compressor crankshaft by removing the unloader valve or head, (refer to the (respective) air
compressor manual.) TDC does not have to be exact. The system is tolerant of some misalignment.
Use ink or dychem to mark the air compressor gear face at TDC (12:00 o’clock position when viewed from the
front.)
Be sure to disengage the timing pin after locating TDC.
Locate TDC for cylinder No. 1 by barring the crankshaft slowly while pushing on the Timing pin.
Rotate the compressor TDC mark to 60 degrees, or 6 teeth on a 36 tooth gear, before TDC. This is approxi
mately 10:00 o’clock when viewed from the front of the air compressor.
NOTE: Holset air compressors Series SS, QE220, 296 and 338 will have a radial line etched on the gear representing
TDC.
