<VV> Serious Problem with Otto Parts TB-20 Camshaft (link to pictures enclosed)

[Joe West]

Hi Gang,

Roughly 8-10 years ago, I rebuilt the engine in my 64 Spyder.  I ordered all
of the rebuild parts from Clarks... Including (for the sake of this
particular discussion) all new lifters, valve springs, new camshaft, thrust
washer, cam gear (and not particularly applicable to this discussion)
pistons, rings, gaskets, etc.

A year or so after the rebuild (roughly) with perhaps 5,000 miles on the
engine, I noticed a vibration in the engine... At a specific RPM.  I polled
this group on the possible causes, but never tracked down the issue...

That is until a few weeks ago.

Upon tearing down the engine... And looking at the camshaft.

The clark's supplied camshaft has one entire lobe completely worn down to NO
LIFT.

Somehow... A single camshaft lobe was completely worn to nothing.
Inspection of the intake valve for this lobe shows that the valve, valve
spring, and all associated parts are working perfectly.  There is nothing
wrong with the head either... Cylinder is perfect.  EVERYTHING is absolutely
perfect... Except for this one lobe on the camshaft.  I broke in  the
camshaft properly and adjusted the lifters cold before I installed the
engine (and then did only minor adjustments after that).

Here's a link to some pictures:

http://www.flatfendertj.com/clarks/clarks.html

I ordered a new camshaft from Clarks (and new gear, thrust washer, lifters,
etc) and have received the new parts and am in the process of rebuilding the
engine.  Now that the engine rebuild is almost complete, I'd like to resolve
this camshaft issue.

Here's the question for the group:

Is there anything I could have done to cause this problem?  Has anyone seen
anything like this?  The ONLY thing I can think of is that somehow this lobe
didn't get hardened properly... But I don't know if this is even possible
given how camshafts are made.

I have contacted Clark's and they have been kind enough to consider giving
me a credit for the new cam and cam gear that I purchased to replace this
defective one (I need to send it back to Clark's for them to take a look
at).

I'd be very interested in everyone's thoughts... And by the way... I'm
pretty pleased that Clark's is being very stand-up about taking care of this
issue for me.



Kind Regards,

Joe West