[TR] Interesting Cam Condition

terryrs at comcast.net terryrs at comcast.net
Sun May 13 06:55:36 MDT 2012


I have become a sudden and sound believer in ZDP.  

When I last rebuilt my engine something like 8 years ago, I bought lifters that Ken Gilanders at British Frame and Engine described as more hardened than usual.  I also sent my cam off somewhere out west to a machine shop to be reground.  

When I broke the engine down in April, what I found was that the lifters on the exhaust lobes were destroyed on the bottom, where the surface was not overly lapped, but rather cratered.  Same on the Camshaft.  Inlet lobes and lifters seemed much better.  (Why would that be?)

8 years ago, the cam came back as bare metal...no seeming special treatment.  This time, I went to a local machine shop I trust.  The reground cam came back covered in black stuff that they tell me is a specially prepared designed layer designed to hold oil and protect the hardened surface until it "laps in."   my friend Barry at the machine shop also gave me a small bottle of ZDP and said to use that instead of assembly lube.  "Then pour the rest of the bottle into the 30 weight non-detergent you'll use to break the engine in."

Question, though.  I would have thought that ZDP would protect from wear as opposed to this deep pitting.  No?

Terry Smith, '59 TR3A
New Hampshire


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