<VV> Engine noise diagnosis on full rebuild

[Bill Meglen]

A friend, a professional mechanic with a Corvair background is working on a
another friends car a 1964 convertible, late 110 engine rebuilt 140 heads.

Rebuild included new crank, Isky cam, lifters, valve train, bearings and
fasteners. It ran fine then at about 490 miles developed what sounded like a
collapsed lifter. The owner found that the noise  diminished at higher rpm.
So he abused it and the clatter morphed into a knock. Initially a lifter was
replaced and showed excessive wear. Complete tear down found a bad crank and
resultant (?) loose main.  Consultation with Clark, tech led to the
conclusion that the crank from another vendor was at fault.  New crank
obtained from Clark¹s. All bearings replaced again. Mains, and rods
plastigaged and everything carefully measured during assembly. Oil passages
carefully cleaned.   The oil pressure relief valves seemed operative but one
was replaced to be safe. Cam was ³run in² again. Engine ran good, oil
pressure 25# at idle 40# at operating speed. Engine has a metallic sounding
tinny noise isolated with a stethoscope to only one bank of engine but not
identifiable to a specific cylinder.  Engine seems to run great.

Recollection on original tear down was that the base engine showed no
evidence that it had been rebuilt. Appeared to be an original unmolested
engine. Very little wear, so indicative of a low mileage engine.  Some
recollection that there was unusual wear on the same lifter that was
ultimately replaced.

While oil passages were cleaned well, oil pressure is good, and relief
valves seem operable there appears to be no way to verify that oil is
reaching the lifters and all parts of engine  needing lubrication.  We all
stumped and only speculate that oil deprivation might be at fault.  Still c
onfident that there was a bad crank but concerned that the problem that
initiated the failure may be in addition to the crank issues.

Welcome any ideas on the problem and its resolution.  A lot of money, time
and anguish is invested in this project.  It appears that everything was
done right but...?