Question for engine builders

[Guest]

Installing some piston pin clips whats the best location for opening in clip when seated in the groove

[chef1366]

As long as they are not in the open area it's good.
A little trick
Put the clip at a ninety degree angle in the bore while squeezing and then rotate into the bore.
No more flying clips.

[Steve]

I have always heard that the opening should be at the top or at the bottom, never on the sides.

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[Jet-Lee]

I've never bothered to make note. I put them in, make sure they're good and tight and not moving, then move on. I'm sure they rotate over the years anyways.

[GSX1000E]

top is where I always put them. I have never seen them moved once installed BTW.

[stetracer]

I have always heard that the opening should be at the top or at the bottom, never on the sides.

.

You are correct.

[stetracer]

I've never bothered to make note. I put them in, make sure they're good and tight and not moving, then move on. I'm sure they rotate over the years anyways.

They do not rotate unless they are bad and not tight enough

[Jet-Lee]

top is where I always put them. I have never seen them moved once installed BTW.

They do not rotate unless they are bad and not tight enough

I also haven't had to open an engine once rebuilt.

Maybe someone could explain the theory behind putting the clips in a specific orientation? Seeing as they're not a component that's under load, it doesn't seem that it should matter.

The piston pin rotates during operation, spinning against the clip. I find it hard to believe that clip does not rotate. Even the piston rings themselves rotate during operation.

[stetracer]

I also haven't had to open an engine once rebuilt.

Maybe someone could explain the theory behind putting the clips in a specific orientation? Seeing as they're not a component that's under load, it doesn't seem that it should matter.

The piston pin rotates during operation, spinning against the clip. I find it hard to believe that clip does not rotate. Even the piston rings themselves rotate during operation.

When the piston changes direction from up to down if the cir clip is installed with the opening on the side. The bottom part of the clip will continue to keep heading up even after the piston has headed down and the opposite happens when the piston changes from down to up. This will eventually weaken the clip.
And ring gap placement is just as important also. They do not rotate either.


.

[Jet-Lee]

I don't believe the clips have sufficient mass for those forces to overcome the clips own outward pressure. The piston doesn't suddenly stop and reverse direction, it gradually slows down and speeds up (gradually being a relative term), it doesn't go from 4200fpm to 0 as if it's hits a wall, the piston slows down as con-rod travels around the perimeter of the crank.

Sorry, I don't buy into that methodology.

I didn't say ring gap placement isn't important, just that the rings rotate in the bore. You don't want all the gaps lined up, but they do rotate. If someone wants to debate that, why do 2-strokes have a ring lock to prevent it?

[chef1366]

I don't believe the clips have sufficient mass for those forces to overcome the clips own outward pressure. The piston doesn't suddenly stop and reverse direction, it gradually slows down and speeds up (gradually being a relative term), it doesn't go from 5800fpm to 0 as if it's hits a wall, the piston slows down as con-rod travels around the perimeter of the crank.

Sorry, I don't buy into that methodology.

I didn't say ring gap placement isn't important, just that the rings rotate in the bore. You don't want all the gaps lined up, but they do rotate. If someone wants to debate that, why do 2-strokes have a ring lock to prevent it?

I marked the ring gap and they do rotate.

[Mekanix]

I don't believe the clips have sufficient mass for those forces to overcome the clips own outward pressure. The piston doesn't suddenly stop and reverse direction, it gradually slows down and speeds up (gradually being a relative term), it doesn't go from 5800fpm to 0 as if it's hits a wall, the piston slows down as con-rod travels around the perimeter of the crank.

Sorry, I don't buy into that methodology.

I didn't say ring gap placement isn't important, just that the rings rotate in the bore. You don't want all the gaps lined up, but they do rotate. If someone wants to debate that, why do 2-strokes have a ring lock to prevent it?

I respectfully disagree :P With the ring lock part.

For the first part though I'd say its a sudden Acceleration and not a sudden stop.
I believe that the sudden acceleration of an explosion pushing a piston down can jar the clip just enough to cause one edge to jump out of the lip and pop out.
Although it would take quite allot of acceleration to overcome the tension of the circlip, I believe its possible with heat, fatigue and hard acceleration.
I think with the clip opening sideways that it would be the easiest way it would fail and with it up or down that it would be the hardest.


And the locating pin on a two stroke would be due to the ports in the sleeve. Notice that the pins are located in a place where the gap placement is in the few places where the liner is continuous for the entire stroke.
Take the exhaust port for instance. Some are nearly 1/4 the circumference of the bore! Imagine what would happen to the ring ends if they stuck out a bit


As far as the rings rotating in a 4 stroke that could be due to vibration's, harmonics, or even the crosshatch in the cylinder.
And hey valve's rotate too

https://www.youtube.com/watch?v=WtqDHJDN79w

[Jet-Lee]

I marked the ring gap and they do rotate.

That's what I said.

I respectfully disagree :P With the ring lock part.

For the first part though I'd say its a sudden Acceleration and not a sudden stop.
I believe that the sudden acceleration of an explosion pushing a piston down can jar the clip just enough to cause one edge to jump out of the lip and pop out.
Although it would take quite allot of acceleration to overcome the tension of the circlip, I believe its possible with heat, fatigue and hard acceleration.
I think with the clip opening sideways that it would be the easiest way it would fail and with it up or down that it would be the hardest.

We agree on one point (it's not a sudden stop) and disagree on the other (whether it's enough to compress the clip). Ok.

And the locating pin on a two stroke would be due to the ports in the sleeve. Notice that the pins are located in a place where the gap placement is in the few places where the liner is continuous for the entire stroke.
Take the exhaust port for instance. Some are nearly 1/4 the circumference of the bore! Imagine what would happen to the ring ends if they stuck out a bit


As far as the rings rotating in a 4 stroke that could be due to vibration's, harmonics, or even the crosshatch in the cylinder.
And hey valve's rotate too
https://www.youtube.com/watch?v=WtqDHJDN79w

Yes, I was saying that piston rings DO rotate. My argument is that piston rings rotate without being acted on by a rotational force. Saying that wrist pin clips don't rotate while the wrist pin itself does, seems foolish to me given that piston rings DO rotate even though neither the piston nor the cylinder rotate.

[chef1366]

I wasn't arguing

[Jet-Lee]

I wasn't arguing

Ah, sorry.