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Recently I have noticed in a quite a few threads that mentioned cam failures . Lobes were " rounding off " , often soon after a " rebuild " .
Several factors were blamed . Proper ZDDP content in the oil , Poor quality "offshore " parts , lack of proper break-in procedure , etc .
Any of those COULD cause a camshaft failure .
But , there is one thing that WILL cause a camshaft failure . And that is improper orientation of the connecting rods during engine assembly .
In the design of the " early Rockets " the camshaft is supposed to be lubricated by what Olds called a " spit hole " . It was a small hole drilled in the side of the rod . When this hole lined up with the oil hole in the rod journal , oil spurted out of this hole . Right toward the camshaft .
These holes must be oriented with the " spit hole " toward the camshaft . If even one rod is mis-oriented that portion of the cam will not be properly lubricated .
I think that this detail in engine assembly might be missed , even by " experts " and " been building engines all my life " types.
Here's a photo from the Oldsmobile Service manual for a better explanation ;
Last edited by Charlie Jones; January 14th, 2018 at 08:51 PM.
This is only speculation , but , The post '64 engines may have better cam lubrication than the "early Rockets" . Olds may have kept them anyway after the 1965 re-design . Just to be on the safe side . Later eliminating them in a " cost cutting " move .
It's a good point about the spit hole. Olds wasn't the only one to use it. I've got an old AMC engine with them also. When changing rod inserts be sure the hole in the insert lines up correctly with the hole in the rod. I once had some that didn't too well requiring a bit of refitting with a proper sized drill.
January 14th, 2018, 08:39 PM
