How many miles since original or the last rebuild? Who did it? Are
you on the last oversize? Was the compression good ? Are you doing
a complete engine O/H? These answers give u a framework for
decision making before disassembly. In my book once u pull an
engine completely apart, its very hard to justify putting it all
back together with used parts. I sometimes make exceptions with
the accessory items which can be gotten at later with engine
re-installed.
OTW look at the piston and cylinder surfaces for deep scratches or
other damage. Is the cross hatching still visible? Excessive top
ridge indicates wear.
If you have inside gauges check wear variance on the cylinder as
per the book, (3 lateral locations). Then if you have the large
mike check the piston diameter and calculate the piston to
cylinder clearance and compare to factory and wear limits.
More crudely check with feelers between the piston (properly
oriented) and its cylinder wall.
The rings are a mute consideration - you are working backwards,
and ps the ring end gap won't tell u much. The ring gap range is
usually quite wide and who knows how good the last mechanic was
with his file. New rings alone are hardly ever the permanent
solution to any significant problem.
If u somehow wind up convincing yourself just to do the rings, at
the very least you will have to hone the cylinders.
Mike L.
60A,67E,59Bug
----- Original Message -----
From: simon hurley <simonsensis@hotmail.com>
To: <mgs@autox.team.net>
Sent: July 17, 2000 7:45 AM
Subject: piston rings worn?
> As part of a rebuild of my 77 B engine I took the pistons out.
How do I
> tell if the rings are worn and need replacing? The cylinders
are in
> excellent condition, no scratches etc.
>
> Thank you in anticipation of your sage advise.
>
> simon
>
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