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Studebaker M15A-20 "Mr. Potato Head"

Sunday, December 23, 2012

Cam Core Plug/Bearing Dilemma

While replacing the rear main seal I discovered that the rear cam core plug was leaking. After removing the plug I discovered that the cam bearing was not installed all the way in the bore preventing the correct cam core plug from fully seating. It appears that the engine rebuilder used a shallow core plug to compensate. I have inserted a stiff wire into the rear oil galley access hole to determine if the cam bearing oil hole is aligned with the block oil hole. One possibility is that the rebuilder DID align the holes but installed the bearing backwards and because the oil hole may be offset it would be recessed on the inside of the engine and protrude on the outside... The only good way to test this is to pressurized the galley and observe if oil is spewing from the bearing.

My current plan if oil does not make it to the cam journal is to press the bearing in and cross my fingers that the oil holes align. If they don't align then I will have to press the bearing out (towards the cam) enough to verify where the oil hole is on the block, align a new bearing and press it in until the holes align, then cut the dangling old bearing off the cam with a Dremel tool cut off wheel. I'm just hoping that the remaining three cam bearings have their oil holes aligned properly...

Original core plug on the right, correct core plug on the left

Rear cam core bore showing the protruding cam bearing

Inside view of rear cam and cam bearing. Note that the bearing is inset about the same distance as the bearing protrudes on the other side.
Cam bearing #3. Note that it is flush with it's bore.

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