The source of the knock

["TJ Noto" <tj@domain.elided>]

Tonight I pulled the big end-cap off the number 3 con-rod and was not
surprised to find that the bearing was wasted.  If you recall, the
engine in Shakespeare had a telltale knock on acceleration.  To me, it
had the unmistakable sound of a rod bearing.  A compression check showed
lower compression in the #3 cylinder, I'm not sure how a rod bearing
failure would lead to that, maybe it's coincidental, but I figured that
the #3 rod bearing would be bad.  The cause of the failure appears to be
either oil starvation or improper assembly.  It overheated at one point
and warped the bearing shell to the point that it does not even fit in
the rod-cap properly.  

This crank appears to have been ground 030 under based on the numbers
stamped on the bearings (conrod).  Does anyone know what the limits are
for a 1600cc crank?  The otherwise pristine crank is in need of a
regrind on that journal so the whole thing will need to be reground.  I
don't think polishing it will clean it up enough.  I'd really like to
not have to get another crank.

I'm still in the process of taking the crank out and the rest of the
components apart, so I'll look for the cause of the failure on this
bearing.

I'll post a picture of the bearing on the website sometime tonight.

Regards,
TJ

TJ Noto		AFM #134  	Cowpoke Racing-"Friends in Slow Places"
http://www.cowpokeracing.com
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