<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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