<VV> 66 Monza 110 PG engine knock - mystery solved

Jedd Hebrink jhebrink at anvilcom.com
Sat Feb 7 17:39:18 EST 2009


Well, I think I finally found the cause of the knock in my recently rebuilt
66 110 PG, (this has been a running saga for months now).  Many of you
offered helpful advice, for which I am very grateful.  Turns out, I spun the
#5 rod bearing.  Probably several possible reasons for this, including a
disconnected front (through the firewall) heater/defroster hose which would
have overheated #5 and #3 especially.  It is also possible I did not have
the rod cap tightened to specs, but I am fairly confident that I did.  I
also used a 50/50 mix of STP and motor oil on all the bearings before
assembly.  The problem wasn't immediate as the engine was running well for a
few hours before the knock appeared.
 
The rod and rod cap as well as the crankshaft journal all appear to be
unscathed.  The bearing took the damage.  My question is this: would it be
wise to install new rod bearings (these were .020) and plastigage and see if
they are within tolerance limits?  Or, would you recommend taking the
crankshaft out and having it machined again?  I really don't want to do
that, but I also don't want to put in new bearings only to have one spin
again.
 
Also, what is the view on replacing the rod bearings on #3 and #5 only?  I
think one of the Corvair vendors sells bearings by the pair.  As you can
tell, I am a cheapskate.  But I don't want to throw away money if that would
be a mistake.  I can Plastigage all six rods, but would expect at least 4 of
6 to be fine since these bearings only have a few hours running time.
 
As always, thanks for your advice.
Jedd Hebrink
 
 

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