<VV> '63 Turbo crank journal clearances

BobHelt at aol.com BobHelt at aol.com
Fri May 30 21:31:08 EDT 2014


Do what you think best, but my Shop Manual says that 3 thou is  max SERVICE 
clearance. I'd suggest that you replace those main bearings.  Running with 
your clearances will lower the oil pressure at idle and likely  illuminate 
the dash light when the oil is hot.
Also, why do you think 5 of 6 rings were cracked? DO NOT use  cast Iron 
rings for your rebuild. Go Moly and the best you can  find.
Just my opinions.
Regards,
Bob Helt
 
 
In a message dated 5/30/2014 5:27:08 P.M. US Mountain Standard Time,  
virtualvairs at corvair.org writes:

Hi

I'm rebuilding my '63 Turbo motor. This is my first  Corvair engine rebuild.
Today we plastigaged  the main bearings for  clearances. We did it by the GM
Service Manual.

Clearances were like  this.

Main Journal #1= .003 (has the different style bearing with  thrust 
surfaces)
#2= .003
#3= .003
#4=  .002
We are thinking that these numbers are within tolerances and I will  not
benefit from replacing these main  bearings with brand new main  bearings. I
would be interested in hearing from more experienced Corvair  engine
rebuilders out there so that I might draw valuable input from  more
experienced Corvair mechanics.

I will not be torture testing  this motor, exceeding red line.
(Intentionally that is!) I do not want to  reassemble it with bearings that
will cause my motor to grenade when I  spool the turbo a bit now and then to
keep the turbo limber. I understand  that missing a gear can undo all of my
hard work by causing an over rev. No  racing.

The problems I found when we opened the engine up were as  follows.

5 of 6 top compression rings were cracked.

#1 piston  skirt was cracked across the skirt but intact.

All 6 skirt clearances  were about .005

I've sent the heads out for rebuild by an experienced  Corvair technician.

I plan on buying new rebored cylinders pistons  & cast iron rings .020 over

The camshaft measured out with very  little wear. I plan on reusing it with
new lifters.

Thanks in  advance.
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