<VV> follow up to no compression in cylinder #3

[Roger Gault]

I, on the other hand, have never had a Corvair engine with OEM pistons that
DIDN'T break at least one piston at the oil ring groove (3 of 3).  I have
replaced all mine over the years with TRW forged.  These days, there are a
number of good pistons available from our vendors - both cast and forged.
Considering the PITA and the $$ involved in breaking another one, I'd
seriously consider changing them all out.  Usually they beat the head
senseless, costing even more money.  The only time I tried replacing one
with a stock piston, I broke another within a year.

YMMV,
  Roger

PS:  I've always run premium fuel - to minimize, but not eliminate, knock.
Suckers broke anyway.


----- Original Message ----- 
From: "Harry Yarnell" <hyarnell1 at earthlink.net>
To: "Jedd Hebrink" <jhebrink at anvilcom.com>; <virtualvairs at corvair.org>
Sent: Monday, March 24, 2008 6:16 PM
Subject: Re: <VV> follow up to no compression in cylinder #3


> This sounds like a broken piston. I've seen this, maybe half a dozen
times;
> always late models. Break is at the oil ring groove, but almost always
> there's one hell of a racket, as the lower and upper piston halves beat
> against each other. Theory is use of the wrong octane fuel causing sever
> knock.
>
> harry yarnell
> poohbah of Perryman
> perryman garage and orphanage
> hyarnell1 at earthlink.net
> ----- Original Message ----- 
> From: "Jedd Hebrink" <jhebrink at anvilcom.com>
> To: <virtualvairs at corvair.org>
> Sent: Monday, March 24, 2008 7:48 PM
> Subject: <VV> follow up to no compression in cylinder #3
>
>
> > Thanks to all who offered suggestions on my question regarding my 66
Monza
> > 110 HP PG.  In the original post I lamented finding no compression in #3
> > while the other 5 cylinders tested at 150 psi.  With the head off, I
have
> > discovered the problem, or at least gotten closer.  I pushed on the #3
> > piston and it slid right back up the cylinder.  (The other pistons
> > remained
> > motionless) There were signs of oil staining along the cylinder wall
along
> > the bottom.  I am not sure what broke.  Any suggestions?  Is it the rod
or
> > wrist pin?  I guess the only way to find out is to yank the cylinder
off.
> >
> > I would value input and suggestions from the group.  Can I get away with
> > just fixing the problem on #3, or do I need to tear down the entire
engine
> > and split the crankcase open?  If the rod is broken, I guess I have no
> > choice but to open the crankcase.  Can I just replace the broken rod, or
> > do
> > I need to replace all six?  What else should I consider replacing if I
> > want
> > to keep this car running?
> >
> > Many thanks,
> > Jedd (I see a long project ahead of me) Hebrink
> >
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> > 6:50 PM
> >
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