| Plymouth Engine >> RESTORING WORN CAM GEAR THRUST SURFACES |
Method To Restore Worn Cam Gear Thrust Area On Some Engine Blocks
Many late model engines (Chevrolet small block and 6.5L (396 CID), Dodge & Plymouth 3.4L (225 CID), Oldsmobile 4.0 & 4.3L (425 & 455 CID), Buick 4.1L (401 CID) and others) do not have camshaft thrust washers, but depend upon the mesh of the distributor drive gear to retain the camshaft. Often the cam gear or sprocket causes the front of the block to wear to such an extent that repair is needed to return the block to service.
A relatively easy yet effective repair is suggested:
(1) Make a metal brush (similar to a cam bearing drive plug) approximately 2 long with the outside diameter to fit the cam bearing housing bore. Provide a slight taper on the O.D. to prevent the bushing from going all the way through. Drill an inner hole in the bushing to accept a valve seat installation pilot. Modify a valve seat cutter shank to be turned by 1/2 electric drill and attach a cutter head proper diameter to match the O.D. of the worn circle.
(2) Cut the front of the block the depth of a Y91 Continental main bearing thrust washer. The O.D. of the thrust washer should be machined to press fit in the machined counterbore. The I.D. of the thrust washer should be machined to fit freely over the cam bushing. The Y91 thrust washer should then be installed.
After tooling up for this operation, the entire procedure should take no more then five minutes and the only cost is that of the thrust washer.
NOTE: Depending upon your valve seat equipment, it may be necessary to change the above tooling to accommodate your equipment.
The AERA Technical Committee
April 1973 - SPB 18
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