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Question for engine builders

  • Thread starter Thread starter 4cyl h2
  • Start date Start date
4

4cyl h2

Guest
Installing some piston pin clips whats the best location for opening in clip when seated in the groove
 
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.
 
I have always heard that the opening should be at the top or at the bottom, never on the sides.

.
 
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.
 
top is where I always put them. I have never seen them moved once installed BTW.
 
Jet-Lee said:
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.
Click to expand...

They do not rotate unless they are bad and not tight enough
 
GSX1000E said:
top is where I always put them. I have never seen them moved once installed BTW.
Click to expand...

stetracer said:
They do not rotate unless they are bad and not tight enough
Click to expand...

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.
 
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Jet-Lee said:
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.
Click to expand...

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.


.
 
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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? ;)
 
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Jet-Lee said:
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? ;)
Click to expand...
I marked the ring gap and they do rotate.
 
Jet-Lee said:
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? ;)
Click to expand...

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 :eek:


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
 
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chef1366 said:
I marked the ring gap and they do rotate.
Click to expand...
That's what I said.

Mekanix 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.
Click to expand...
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.

Mekanix said:
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 :eek:


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
Click to expand...

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.
 
Jet-Lee said:
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.
Click to expand...

Rings yes, as others have stated.
The ends of the piston pin are chamfered so that any end thrust on the pin will push the circlip harder into the groove. Given this and that the circlip ends are deliberately left sharp, i'd doubt if you'd see any rotation under normal use.
I've had properly installed circlips pop out - but it's taken a massive overrev to do it. Inertia will eventually overcome circlip preload in the groove.
 
It is the change of piston direction
That causes the stress on the cir clip. At 10,000rpm your piston is going up and down 166 times a second. At 10 mph if you hit a brick wall with a 100 lbs it will have 10 times the force. That is why little kids were getting killed in little fender benders sitting in there mothers lap even though mom only weighed 100lbs at 10 mph she was crushing the baby with a 1000 lbs of force and it is even greater at higher speeds. So that little cir clip at 10,000rpm is fighting a lot of weight when placed in sideways

.
 
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So I don't have to worry about my ring gaps placement I can just line them all up on the exhaust side from now on as the are going to line up sometime while the motor is running anyway.
I guess I worry about to many little details
 
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