<VV> Rod Bearings

[Brown, David]

Bob,
The answers are below, in your message.  There are a few assumptions, so the
answer(s) may never be known.
Dave

  _____  

From: BobHelt at aol.com [mailto:BobHelt at aol.com] 
Sent: Saturday, June 11, 2005 2:51 PM
To: Brown, David; virtualvairs at corvair.org
Subject: Re: <VV> Rod Bearings


In a message dated 6/11/05 10:20:15 AM US Mountain Standard Time,
BrownD at bsci.com writes:



but I wanted to get some
opinions about rod bearings.  My basic question is why did they wear out so
fast in my engine?



David, 
There are too many unknowns here for an accurate guess. Below are some
considerations that should be analyzed if you hope to get an answer.

Was just the one rod bearing worn, or are the rest worn too? 
--> Only 1 has been pulled so far.  The rest will be when I get the
replacements.  I am assuming they are all similar. 

When assembled (rebuilt previously) was assembly lube used on the bearings? 
--> I hope/assume so.  The engine was built by a very reliable full time
mechanic, who is also a life long Corvair mechanic well respected in the
club.

What were the bearing clearances set to then? 
--> The crank journals were ground for .10", which was what was installed.

What type of rod bearings were used? Were they Moraine 400? (i.e.,
aluminum?) or tri-metal? 
--> Not sure- whatever came from Clark's at the time (2001). 

At what point(s) was the bearing worn, how big was the worn spot, and
location? 
--> Smooth wear throughout the whole bearing surface. 

What is the condition of the crankshaft journal? Is it out of round/tapered?
An OOR journal could be the cause of your problem. 
--> The crank was ground by "regular" machine shop always used for this type
of work by this mechanic, so I assume  it was OK.

It would be a good idea to now measure the bearing clearance with the worn
bearing to see how bad the wear was. Then check the journal as described. 
--> Yes, this will be done.  Not sure what it is yet. 

Regards,
Bob Helt