Crankshaft Gear/Sprocket: Service and Repair

Fig. 29 Camshaft gear removal. 6-250 & 292:

Fig. 30 Checking camshaft endplay. 6-250 & 292:

6-250, 292
When necessary to install a new camshaft gear, the camshaft will have to be removed as the gear is a pressed fit on the shaft. The camshaft is held in position by a thrust plate which is fastened to the crankcase by two capscrews which are accessible through two holes in the gear web.
Use an arbor press to remove the gear and when doing so, a suitable sleeve, Fig. 29, should be employed to support the gear properly on its steel hub.
Before installing a new gear, assemble a new thrust plate on the shaft and press the gear on just far enough so that the thrust plate has practically no clearance, yet is free to turn. The correct clearance is from .001 inch to .005 inch. Fig. 30.
The crankshaft gear can be removed by utilizing the two tapped holes in conjunction with a gear puller.

Fig. 31 Valve timing marks. 6-250 & 292:

Fig. 32 Checking timing gear backlash. 6-250 & 292:

Fig. 33 Checking timing gear runout. 6-250 & 292:

When the timing gears are installed, be sure the punch-marks on both gears are in mesh, Fig. 31. Backlash between the gears should be from .004 inch to .006 inch, Fig. 32. Check the runout of the gears, Fig. 33, and if the camshaft gear runout exceeds .004 inch or the crank gear runout is in excess of .003 inch, remove the gear (or gears) and examine for burrs, dirt or some other fault which may cause the runout. If these conditions are not the cause, replace the gear (or gears).