Three Ring Set in a Four Ring Groove Piston

[davidbraley]

Gentlemen,

Because I’m still very new to my hobby of engine building (I am no pro for sure), I need your help with some questions I’m having trouble finding answers to.

For a vintage (ish), non-hi-performance engine project I’m still slowly collecting parts for, I’m going to try and use a set of Sealed Power pistons, part # H811CP. These pistons have 4 ring grooves. Three compression ring grooves, and the oil ring groove at the bottom.

The Sealed Power catalog shows two different ring sets specifically for this piston. One ring set has only two compression rings, and the second has three. Both ring sets have a moly-faced top ring. I found it very interesting that both of these ring sets are an option for this piston. If someone knows why, I would love to know.

If it helps, at the bottom of this post, I show an image of the piston I’m going to try and use, and some screen-shots from the Sealed Power catalog.

By now, I’m sure some of you have already guessed what my questions are:

If I use the ring set with only two compression rings, which compression ring groove on the pistons do I leave empty? The groove just below the top ring? Or the bottom compression groove just above the oil ring?

Just for fun, I’m going to guess that the top two compression ring grooves on the pistons should be filled. The third compression ring groove is left empty. Did I guess this right?

Thanks in advance for your patience and help.

David

[hoodeng]

That will work fine with the third comp groove empty, when using a quality three ring set.

The multiple comp grooves were used when there was just a stack of soft cast iron rings on the piston.

[davidbraley]

That will work fine with the third comp groove empty, when using a quality three ring set.

The multiple comp grooves were used when there was just a stack of soft cast iron rings on the piston.

Thank you sir!

[RCJ]

Rebuilt a 1930s farm all with 4 rings. Was a hand crank, could not crank it by hand after rebuild. If I was doing it again I would put spacers in the grooves and run a moly ring that was thinner. And leave the 3rd ring out