<VV> re-ringing

[djtcz at comcast.net]

----- 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. The 
"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. 

Thanks, 
Ned 
================================== 
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. 


http://www.deves.com/tips.cfm 


http://www.hastingsmfg.com/ServiceTips/cylinder_deglazing.htm 


http://www.hastingsmfg.com/ServiceTips/breakin_procedure.htm 


http://www.hastingsmfg.com/techtips.htm