Piston Circlips.


jabcamit@...
 

Glen recently reported on poor piston circlip  groove machining.  There have also been problems in the past resulting from wire circlips rotating and wearing away the groove and/or the wire diameter being too thin to provide adequate pin retention. Also difficulties with removing some types of circlip.  What's the latest advice  is on circlip upgrade when  re-assembling  earlier engines?   What do Camit do?

BobP


David Amsler
 

The CAMit engines used wire circlips with the ends of the wrist pins tapered so that when they pressed against to wire clips, they pushed the clips outward, tighter into the grooves.  The wire clips have a small tail a few mm long that points outward from the center, and a corresponding notch is cut into the piston so that they cannot rotate.  I have not been able to locate any pictures of this in my files, and am a bit reluctant to pull a barrel to take a picture.   The following is part of a list that Ian presented as improvement made in his engines.

3. Pistons
Issues addressed:
Loose/lost circlips; easier circlip removal, jammed rings, cooler pistons, reduced wear, faster break-in, reduced piston slap loads with worn bore clearance.
a. Modified wire circlips – standard solid lifter with anti-rotation tails
b. Pockets for circlip tails
c. Rings – honing changed to suit standard tension rings
d. Ring groove width – standard for solid lifter engines
e. Piston pin length – to suit wire circlips
f. Reversed orientation – piston pin offset to thrust side – standard engineering practice.

David A.

On Fri, Apr 23, 2021 at 6:22 AM <jabcamit@...> wrote:
Glen recently reported on poor piston circlip  groove machining.  There have also been problems in the past resulting from wire circlips rotating and wearing away the groove and/or the wire diameter being too thin to provide adequate pin retention. Also difficulties with removing some types of circlip.  What's the latest advice  is on circlip upgrade when  re-assembling  earlier engines?   What do Camit do?

BobP


David Amsler
 

Just to further confuse this piston issue, In my previous post, the last item in Ian's list of improvements was to - reverse the orientation of the piston offset - and I now wonder if orientation has any effect on breakage ?

David A.

On Fri, Apr 23, 2021 at 8:03 AM David Amsler <energyhawk@...> wrote:
The CAMit engines used wire circlips with the ends of the wrist pins tapered so that when they pressed against to wire clips, they pushed the clips outward, tighter into the grooves.  The wire clips have a small tail a few mm long that points outward from the center, and a corresponding notch is cut into the piston so that they cannot rotate.  I have not been able to locate any pictures of this in my files, and am a bit reluctant to pull a barrel to take a picture.   The following is part of a list that Ian presented as improvement made in his engines.

3. Pistons
Issues addressed:
Loose/lost circlips; easier circlip removal, jammed rings, cooler pistons, reduced wear, faster break-in, reduced piston slap loads with worn bore clearance.
a. Modified wire circlips – standard solid lifter with anti-rotation tails
b. Pockets for circlip tails
c. Rings – honing changed to suit standard tension rings
d. Ring groove width – standard for solid lifter engines
e. Piston pin length – to suit wire circlips
f. Reversed orientation – piston pin offset to thrust side – standard engineering practice.

David A.

On Fri, Apr 23, 2021 at 6:22 AM <jabcamit@...> wrote:
Glen recently reported on poor piston circlip  groove machining.  There have also been problems in the past resulting from wire circlips rotating and wearing away the groove and/or the wire diameter being too thin to provide adequate pin retention. Also difficulties with removing some types of circlip.  What's the latest advice  is on circlip upgrade when  re-assembling  earlier engines?   What do Camit do?

BobP


Jay Scheevel
 

Is there an epidemic of piston failures, or am I missing something? Seems like this has happened only occasionally (most recently in John’s Gen 4 engine), and certainly less often than valve failure or through bolt failure, regardless of generation of engine. Am I wrong?

 

Jay

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of David Amsler
Sent: Friday, April 23, 2021 6:06 AM
To: main@jabcamit.groups.io
Subject: Re: [JabCamit] Piston Circlips.

 

Just to further confuse this piston issue, In my previous post, the last item in Ian's list of improvements was to - reverse the orientation of the piston offset - and I now wonder if orientation has any effect on breakage ?

 

David A.

 

On Fri, Apr 23, 2021 at 8:03 AM David Amsler <energyhawk@...> wrote:

The CAMit engines used wire circlips with the ends of the wrist pins tapered so that when they pressed against to wire clips, they pushed the clips outward, tighter into the grooves.  The wire clips have a small tail a few mm long that points outward from the center, and a corresponding notch is cut into the piston so that they cannot rotate.  I have not been able to locate any pictures of this in my files, and am a bit reluctant to pull a barrel to take a picture.   The following is part of a list that Ian presented as improvement made in his engines.

 

3. Pistons
Issues addressed:
Loose/lost circlips; easier circlip removal, jammed rings, cooler pistons, reduced wear, faster break-in, reduced piston slap loads with worn bore clearance.
a. Modified wire circlips – standard solid lifter with anti-rotation tails
b. Pockets for circlip tails
c. Rings – honing changed to suit standard tension rings
d. Ring groove width – standard for solid lifter engines
e. Piston pin length – to suit wire circlips
f. Reversed orientation – piston pin offset to thrust side – standard engineering practice.

 

David A.

 

On Fri, Apr 23, 2021 at 6:22 AM <jabcamit@...> wrote:

Glen recently reported on poor piston circlip  groove machining.  There have also been problems in the past resulting from wire circlips rotating and wearing away the groove and/or the wire diameter being too thin to provide adequate pin retention. Also difficulties with removing some types of circlip.  What's the latest advice  is on circlip upgrade when  re-assembling  earlier engines?   What do Camit do?

BobP


Mick O'Connor
 

Beware, piston offset has re-emerged.
Mick

On 23 Apr 2021, at 15:47, Jay Scheevel <jay@...> wrote:

Is there an epidemic of piston failures, or am I missing something? Seems like this has happened only occasionally (most recently in John’s Gen 4 engine), and certainly less often than valve failure or through bolt failure, regardless of generation of engine. Am I wrong?

 

Jay

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of David Amsler
Sent: Friday, April 23, 2021 6:06 AM
To: main@jabcamit.groups.io
Subject: Re: [JabCamit] Piston Circlips.

 

Just to further confuse this piston issue, In my previous post, the last item in Ian's list of improvements was to - reverse the orientation of the piston offset - and I now wonder if orientation has any effect on breakage ?

 

David A.

 

On Fri, Apr 23, 2021 at 8:03 AM David Amsler <energyhawk@...> wrote:

The CAMit engines used wire circlips with the ends of the wrist pins tapered so that when they pressed against to wire clips, they pushed the clips outward, tighter into the grooves.  The wire clips have a small tail a few mm long that points outward from the center, and a corresponding notch is cut into the piston so that they cannot rotate.  I have not been able to locate any pictures of this in my files, and am a bit reluctant to pull a barrel to take a picture.   The following is part of a list that Ian presented as improvement made in his engines.

 

3. Pistons
Issues addressed:
Loose/lost circlips; easier circlip removal, jammed rings, cooler pistons, reduced wear, faster break-in, reduced piston slap loads with worn bore clearance.
a. Modified wire circlips – standard solid lifter with anti-rotation tails
b. Pockets for circlip tails
c. Rings – honing changed to suit standard tension rings
d. Ring groove width – standard for solid lifter engines
e. Piston pin length – to suit wire circlips
f. Reversed orientation – piston pin offset to thrust side – standard engineering practice.

 

David A.

 

On Fri, Apr 23, 2021 at 6:22 AM <jabcamit@...> wrote:

Glen recently reported on poor piston circlip  groove machining.  There have also been problems in the past resulting from wire circlips rotating and wearing away the groove and/or the wire diameter being too thin to provide adequate pin retention. Also difficulties with removing some types of circlip.  What's the latest advice  is on circlip upgrade when  re-assembling  earlier engines?   What do Camit do?

BobP


glen english LIST
 

To my knowledge and my ear out, there has not been alot of piston smashing in recent times, I think only a few a year .
There was quite a alot of them 2005-2013.

and John's Gen4- was deemed workshop assembly problem I thought ?? and that was before the new solid pistons ?

On 24/04/2021 12:47 am, Jay Scheevel wrote:
Is there an epidemic of piston failures, or am I missing something? Seems like this has happened only occasionally (most recently in John’s Gen 4 engine), and certainly less often than valve failure or through bolt failure, regardless of generation of engine. Am I wrong?
Jay