I'm glad i am rebuilding a second motor, and not the
one out of the van, as i certainly am taking my time
with this...

I have something i am a little confused by, now,
regarding the big end rod bearing clearance.  Bentley
clearly specify a rod bearing clearance between
.0254mm-.05mm (.001-.002in), with the crank's rod
journal diameter between 54.983mm-54.996mm
(corroborated by Haynes).  The rod housing bore is
called out to 57.8mm-57.818mm (2.2756-2.2763in).

My parts measure out to:
rod housing bore = 57.8mm-57.81mm (all rods - measured
with an inside snap guage and measured with digital
calipers - both mitutoyo)
crank rod journal diameters = 54.97mm (#4 = 54.98)
Rod bearing measures out at 1.38mm thick (std.
kolbenschmidt)

So: 57.8 - (54.97+1.38*2) = 0.07mm clearance.  This
also, fortunately, matches up to the measured rod
bearing inside diameter of 55.04mm when mounted up.
Plastiguage also confirms this (about .08, actually)

What i don't get is that the crank and rod bore are
within spec, so a std. rod bearing should be what you
want, right?

A +.010 (+.254mm) bearing measured at 1.51mm thick,
which would add up to:
57.8 - (54.97+1.51*2) = .19mm interference.

Obviously, i am missing something.  I *think* i know
how to use a caliper (sarcasm), and it is reasonably
accurate (.0005"/.01mm), and i am getting consistent
measurements (and i've done them many times by now!).

Any help would be appreciated.  Of course, it could be
something bonehead like not realizing that the
specified rod bearing clearance is the nominal gap all
the way around, not justified to one side (ie.
diameter difference, not radius, which would halve my
results, magically making everything perfect?).

I'll just work on clearancing the rod/camshaft
interference until i figure out why the rods don't
seem right...

Thanks,

-Damon

=====
'84 Westy (Sparky)
'65 Kharma Ghia (Dharma)

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