<VV> re-ringing

AeroNed at aol.com AeroNed at aol.com
Thu Nov 25 16:06:04 EST 2010

Happy Thanksgiving! and thanks for the tips.
I am going to be rebuilding the engine at a machine shop. Anyone remember  
Glen Ziesenis? Well, I'll be at his shop. I'm planning to rebore the 
cylinders  and he has the fixture to do that under compression. I'll also be 
rebuilding the  head and doing a valve job.
I'm still curious about doing a re-ring job. Maybe I need to find a good  
engine and experiment.
I've rebuilt engines before, even a couple Corvairs. The last time I  
rebuilt the rods and did a valve job at Glen's shop. Both firsts for me. This  
time will be the first rebore for me. I'm hoping to keep the  compression down 
so I can still use unleaded and not generate too much heat when  running 
the AC.
Thanks Again,
In a message dated 11/25/2010 9:01:16 A.M. Central Standard Time,  
djtcz at comcast.net writes:

-----  Original Message ----- 
Date: Wed, 24 Nov 2010 19:39:06 EST 
From:  AeroNed at aol.com 
Subject: <VV> Re-ringing 

My winter project  is going to be the rebuilding of a 95 hp engine to go in 
my 65 coupe. This  engine will be hooked to a PG and will be running AC. 
"core" engine is  a runner that smoked when removed. I'm thinking it may 
only need rings  (and new bearings and other while I'm there parts). 

Anyhow, I've heard  all sorts of stories about re-ringing a Corvair engine, 
most of them bad.  I'd like to hear some of the good ones. I really would 
like to keep the  bore stock. What are the "tricks" I'll need to know to do 
this right.  

The back of  the Corvair shop manual has a "Specification" section. On the 
one or two  engine pages there are some key dimensions that must be within 
service limits  to achieve decent performance and life. 
An area that may be easy to  overlook is how much clearance the new rings 
have in the used pistons (or even  new ones). Check with a feeler gage. 
Don't blast piston ring grooves clean  with any abrasive, since the rings 
must seal against the groove walls, and the  groove's finish and form can be 
destroyed by blasting. Cleaning carbon from  the grooves grooves with a 
broken ring can do some damage too. 
ANy ridge  worn at the top of the cylinder must be removed to keep the top 
ring from  jamming in the "corner" right at TDC. Every Cylinder's roundness 
and taper  needs to be measured and evaluated honestly. Surface finish is 
important, but  there is a range of acceptable roughnesses. Inadequate 
cylinder cleaning will  tear up new rings quickly, and I suspect may be behind many 
of the "darned  rings didn't seat" stories. A few squirts of carb cleaner 
is not good enough.  One good test is An oiled white rag must stay clean 
after being scrubbed  against the "cleaned" cylinder wall. 
During end gap checking I like to put  each new ring in the cylinder, near 
the top of it's travel, square it off by  inserting a flat topped piston, 
and backlight the ring with a flashlight and  look for light at the cylinder 
wall. Visible light indicates cylinder ovality  beyond the ring's 
capabilities to conform. Or maybe tweaked rings. End gap  needs to be checked where it 
is tightest, in the smallest portion of the bore,  usually near BDC. In the 
quest for tight end gaps some folks start with an  oversize ring. That is 
probably OK, as long as when finished the ring passes  the back light test. 

Oil Smoke can originate from valve stem,  guide, and seal issues, as well 
as crankcase ventilation problems too.  




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