[Fot] Snap Rings in Pistons

[Ponostyle]

Steve—what!! These are pretty much standard pin rings, used in all motorcycles and most cars. I rarely saw an engine with snap rings until recently. You put these in by hand—push one end into the grove and roll the ring in. You can check to make sure they are seated by giving them a gentle shove with a flat blade screwdriver. To take them out, get a small screwdriver that fits into the slot at the bottom of the wrist pin hole (now you know what that slot is for), slip the blade under the ring and ease it out. I’ve never had one hit me in the eye, but I had one fly into my mouth once—so keep your mouth closed and wear safety glasses. They should be single use retainers, but mediocre mechanics everywhere reuse them if they took the piston off the conn rod for some reason but aren’t replacing it with a new piston (which comes with them). Best practice calls for positioning the ring so the opening is on top. Acceleration of the piston is vertical (of course) so a sideways opening could allow the ring to close a bit under acceleration and come loose. It probably hasn’t happened in the entire history of engines, but it’s pretty to think about. 

I used to carry a few extras in my mechanics apron when I worked in a shop. If one of the other mechanics had pranked me (a common thing) I'd wait until he was putting the engine back in and drop one on his bench. 

Bill Babcock
Beach Bum
bill at ponostyle.com
https://www.Ponostyle.com

> On Jan 22, 2023, at 9:18 AM, Steve Yott via Fot <fot at autox.team.net> wrote:
> 
> I have seen a ton of retaining rings in my life but those take the dumb cake.  I would recommend measuring the needed size and order them from McMaster Carr.  Even if you install those the next person will need to bugger up the pistons to get them out!
> 
> Steve Yott
> 
> 
> 
> Steve Yott
> 
> 
> -------- Original message --------
> From: Jack Wheeler via Fot <fot at autox.team.net>
> Date: 1/22/23 12:18 PM (GMT-06:00)
> To: FOT Triumph <fot at autox.team.net>
> Cc: "J.S. Zimmerman" <jzimme10 at gmail.com>, Eva Golding <ken at davebean.com>
> Subject: [Fot] Snap Rings in Pistons
> 
> I am trying to install the snap rings which hold the wrist (gudgeon?) pins in the pistons.  The snap rings I have used on the TR-3/4 engines and most of the other engines I have rebuilt, have small holes in the ends.  These allow you to insert snap ring pliers into the holes so you can squeeze the snap rings into place in the grooves in the piston bores.
> 
> I am assembling a Ford 1600 CC engine for my Morgan and have bought new pistons.  The snap rings that came with these pistons do not have the holes in the ends.  See attached picture.
> 
> These snap rings are very stiff and I can't squeeze them in by hand.  I also can't figure out a way to grip them with the snap ring pliers I have.  Does anyone know if there is a special tool I need to use to install these?  Or any suggestions about how I should go about installing them?  Thanks.
> 
> Jack Wheeler
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