PROJECT 51: Tappets and Cam. When I took the tappets and cam out of the engine block I set them aside, to be cleaned later. A quick look at the cam lobes showed no unusual signs of wear, or marks that would indicate any kind of problem, and I expected to be able to reuse them.
When I got around to cleaning the tappets, I did notice some unusual wear. It's probably just the result of many tens-of-thousands of miles on the engine (I don't know the actual mileage on the car), but improper valve-clearance adjustment could have played a part, too. The clearance needed such constant attention on these engines that the valve cover is held on with two big hand knobs rather than nuts, the clearance is specified on a brass plate riveted to the cover, and the factory tool kit came with a box wrench for the rocker nuts and the proper-thickness feeler-gauge.
After seeing the wear on the tappets, I inspected the cam more closely. I used micrometers to check the lift on the lobes and compared the measurements to the shop-manual specs. Only two of the eight lobes were within acceptable limits. The others showed wear all the way down to .030" undersize. I calculated that that would mean those valves were opening more than 20% less than their partners. This little four-cylinder engine must have run like a clothes dryer with sneakers inside!
A new set of tappets, cam, and pushrods is on the way. The cam will also get a new set of bearings installed in the block.
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| Bottom surface of tappets. Very unusual pitting. |
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| Cam was inspected with micrometers. |
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| Valve cover with hand knobs for easy (frequent) removal, and brass plate indicating proper rocker-to-valve clearance. |
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