Sorry, but I still can't figure out "between gudgeon pin and away from left
hand (thrust)
side of piston". [The 4.0/4.6 section of the manual adds "thrust".] When I see
the word
"between", I expect to see "between x and y", that is, two items. The manual
goes on to
say "Position compression rings with ring gaps on opposite sides of piston
between gudgeon
pin and right hand side of piston -- viewed from front of piston." Note that
there is no
differenciation between the left and right bank. They seem to be saying that
the gaps will
be on the high side for one bank and on the low side for the other bank. My
buick manual
says "Position ends of expander above the piston pin where groove is not
slotted." This
does imply that the banks are treated differently, possibly agreeing with
Glenn. But does
Buick really want the gap at the front or back of piston, "where the groove is
not
slotted"? Both sides of my Rover pistons are slotted in the oil ring groove.
Only above
the ends of the pin (ie, front and back of piston) is the Rover oil control
groove not
slotted. A ford V-8 manual wants the expander gap at the very back of the
piston for all
eight pistons. All very confusing, except for what Ford wants: Ford shows a
circle
representing the top of the piston, and all the gaps shows on that circle, like
the hands
of a clock.
Regarding left and right, the Rover manual (LRL 0164 and LRL 0004) explicitly
says "viewed
from front of piston", contrary to the norm of sitting behind the steering
wheel.
Jon
----- Original Message -----
From: <trevor_easton@dofasco.ca>
To: <StagByTriumph@tscusa.org>; <jonnyaxt@iinet.com>;
<buick-rover-v8@autox.team.net>
Sent: Tuesday, January 09, 2007 6:05 AM
Subject: RE: piston rings
The orientation with respect to driver and front is correct, but I believe the
reason is
so that the gap is on the pressure side of the piston during the firing stroke
(left is
down on left bank and up on right bank after all) The gaps should be positioned
in the 45
degree angle on the right side of the piston but not all in line. The object of
this is
SFAIK to reduce the chances of ring vibrations and subsequent breakage.
________________________________
From: owner-buick-rover-v8@autox.team.net on behalf of StagByTriumph@tscusa.org
Sent: Mon 08/01/2007 19:33
To: jonnyaxt@iinet.com; buick-rover-v8@autox.team.net
Subject: RE: piston rings
Hi John,
Pistons have a "front" which is positioned to the front of the engine
block. It is usually marked with an arrow, or text stamped into the top of
the poston. That is in line with the wrist pin and aligns the underside
oiling.
Engine left is as you are sitting in the driver seat (left or right hand
drive).
Left as refered to in the manual is for the down side of the piston, or
left side of the piston. This is so the gap is not sitting where fuel or
oil might easily travel by gravity past the piston into the sump. If the
gaps are on the up side, then fuel and oil will sit on the ring ready for
the next start.
Glenn Merrell
President, TSC USA
Original Message:
-----------------
From: jon jonnyaxt@iinet.com
Date: Mon, 8 Jan 2007 15:57:38 -0800
To: buick-rover-v8@autox.team.net
Subject: piston rings
My Rover (published by Rover) engine manual says "Position oil control
expander ring joint
and ring rail gaps all at one side, between gudgeon pin and away from left
hand side of
piston - viewed from front of piston." I know that gudgeon pins are really
wrist pins, but
my pistons are round and don't have sides. I can't make any sense of this.
How do I
position the ring gaps -- oil control and compression? Jon
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