Installing Piston Pin Clips (by hand or with snap-ring pliers)?

[dibbons]

A recent posting on a 273 rebuild video states the clips should be installed by hand. I'm not sure about that, but who knows?

"A little story for you. I built my 354 engine myself and used pliers to put those clips in. Well, those are not tempered spring clips and they are not meant to put in with pliers. They’re meant to put in with your fingers like you did it first. I squeezed one a little too hard and although it snapped in place, it did not stay in place and during startup it got spit out and the engine stopped. I restarted it and it ran fine not realizing what had happened. 600 miles later and lots of oil I scoped the cylinder to see that the piston pin I had cut a very large groove in my beautiful new block."

rebuild video where the comment was posted:

 

[toolmanmike]

I used needle nose pliers if I remember right. Although, that was almost 15 years ago. They were the wire type and not a real snap ring.

 

[dibbons]

I'm sure the comment was referring to the "old-fashioned" snap ring in photo.

 

[toolmanmike]

I'm sure the comment was referring to the "old-fashioned" snap ring in photo.

View attachment 1716391097

Sorry, as far as I know the stock clips were wire. That is a standard snap ring and of course it should be installed with snap ring pliers. Mine looked like this.

 

[dibbons]

Those I removed from the 340 (0.040 over) I purchased are like the photo in post #3.

Here is a previous FABO discussion:

factory style piston pin snap rings source?

 

[hemifiedbird]

Depending how the Snap rings are installed is very Important. The open end of the snap ring should be at the bottom of the pin hole. That way when you have the explosion due to firing of the cylinder. It puts pressure pushing down on the piston and Pin retainers and if the open part of the snap ring is at the bottom it applies pressure down on the top of the Snap ring which pushes the sides out to keep it in the ring groove. If it is at the top the downward pressure can push the ends out of the groove and the snap ring pop out. It happens in Big Industrial Diesel Engines and have seen it in gas engines as well. Quite a few engine builders just put the ring in without worrying about orientation of the snap ring.

 

[toolmanmike]

Depending how the Snap rings are installed is very Important. The open end of the snap ring should be at the bottom of the pin hole. That way when you have the explosion due to firing of the cylinder. It puts pressure pushing down on the piston and Pin retainers and if the open part of the snap ring is at the bottom it applies pressure down on the top of the Snap ring which pushes the sides out to keep it in the ring groove. If it is at the top the downward pressure can push the ends out of the groove and the snap ring pop out. It happens in Big Industrial Diesel Engines and have seen it in gas engines as well. Quite a few engine builders just put the ring in without worrying about orientation of the snap ring.

Also, the flat side should go in. The rounded side out.

 

[dibbons]

Also, the flat side should go in. The rounded side out.

I found this other comment on this site somewhere-hard to say if this in agreement with toolman or is he saying the opposite?

 

[dibbons]

From JE pistons:

"Generally Tru Arcs are the easiest to install and are more popular in lighter duty applications. The snap ring or Tru Arc is easily installed using dedicated pliers. The tips of these pliers fit into the holes at the ends of the snap ring. When the pliers handles are squeezed, the snap ring compresses enough to firmly seat into the retaining groove on the piston. A word of caution: snap rings are manufactured with a smooth and rough side. Be sure the smooth side faces the wrist pin. Also, install the snap ring with the open end pointing down."

Not sure what they mean by smooth and rough but I will have to take a look at 'em.

Article:

Wrist Pin Locks: Different Styles and How To Install Them

 

[Max1196]

Also, the flat side should go in. The rounded side out.

Gota say no to that. Flat side of clip to the outside and curved side of the clip towards the wrist pin.

 

[Bossanova5]

This is the wrist pin clip removed from my 273.
From what I can tell it is the original from a 66/67