TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
A/C Cylinder Head (SS 191 Model) (012-101)
Section 12 - Compressed Air System - Group 12
Page 12-33
Install (012-101-026)
Air Compressor Timing (for single-cylinder air com-
pressor only)
Locate TDC on the compressor crankshaft by removing the
unloader valve or head (refer to the respective air com-
pressor manual). TDC does not have to be exact. The
system is tolerant of some misalignment.
Use ink or dykem to mark the air compressor gear face at
TDC (12-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 approximately 10-
o'clock when viewed from the front of the air compressor.
NOTE: Holset air compressors Series SS, QE296 and 338
will have a radial line etched on the gear representing TDC.
L-1237