Sealed Power Piston Rings

[Mark H.]

I am in the process of grinding piston rings prior to engine reassembly. I'm not very good at it, and overshoot the mark more often than I would like, which means I needed to buy a second set of rings. My block is bored .40 over, so I'm using Sealed Power ring set E-251K 40. The first set of rings I bought came in a box with a 2005 copyright. The second had a 2010 copyright. The first set had different shades of green paint marking the top and second ring. No marks on the second set. The top ring looks identical from set to set, apart from the second set lacking any dimple. The second ring, however, is different. The bevel is much more pronounced on the second set than the first set. Anyone know why, and (more importantly) is it significant enough that I should not use some from the first set and some from the second (and yes, I already overground one from the second set). Really don't want to buy a third set.

Thanks.

Mark

[Joe L.]

Re: Sealed Power Piston Rings

I am in the process of grinding piston rings prior to engine reassembly. I'm not very good at it, and overshoot the mark more often than I would like, which means I needed to buy a second set of rings. My block is bored .40 over, so I'm using Sealed Power ring set E-251K 40. The first set of rings I bought came in a box with a 2005 copyright. The second had a 2010 copyright. The first set had different shades of green paint marking the top and second ring. No marks on the second set. The top ring looks identical from set to set, apart from the second set lacking any dimple. The second ring, however, is different. The bevel is much more pronounced on the second set than the first set. Anyone know why, and (more importantly) is it significant enough that I should not use some from the first set and some from the second (and yes, I already overground one from the second set). Really don't want to buy a third set.

Thanks.

Mark

Mark------


I don't understand why you're having to do all this ring end grinding. If you have a 40-over bore, have 40-over pistons, and are using 40-over rings, there should be very little ring end grinding required. And, when some adjustment is necessary, it should be minimal. So, how you are ruining a lot of rings by over-grinding confounds me.

As far as the difference in the rings, if the rings sets are of the same part number, the rings should be interchangeable. Of course, the later design represents an improvement but it should not affect interchangeability or usability.

[Mark H.]

Re: Sealed Power Piston Rings

I have Keith Black pistons. Top ring out of the box is around 15 thousandths, needs to be 27. Second ring is 15 to 16 out of the box, needs to be 17. Top and bottom ring for the third, three-piece ring is in the 20s out of the box I think, and needs to be 65. I try very hard to creep up on the spec, but sometimes go 2 or 3 thousandths over. I must not apply the same amount of pressure against the grinding disk (hand crank) each time, because the same number of revolutions does not remove the same amount of material each time. I ruined 4 of the 8 top rings in the first set and a couple of the second and third rings.

[Joe L.]

Re: Sealed Power Piston Rings

I have Keith Black pistons. Top ring out of the box is around 15 thousandths, needs to be 27. Second ring is 15 to 16 out of the box, needs to be 17. Top and bottom ring for the third, three-piece ring is in the 20s out of the box I think, and needs to be 65. I try very hard to creep up on the spec, but sometimes go 2 or 3 thousandths over. I must not apply the same amount of pressure against the grinding disk (hand crank) each time, because the same number of revolutions does not remove the same amount of material each time. I ruined 4 of the 8 top rings in the first set and a couple of the second and third rings.

Mark-------


OK, now I understand. With the Keith Black hypereutectic pistons the out-of-the-box ring gaps will not be correct. For a long time I have hoped that United Engine, the manufacturer of Keith Black pistons, would offer piston ring sets for their pistons with the correct end gaps. So far, though, no luck.

[Duke W.]

Re: Sealed Power Piston Rings

Hi Mark... got your email. I've never filed a set of rings, but I believe you can buy "file to fit" sets, and I expect there may be a special file than needs to be used. It's very important to follow the KB instructions for minimum top ring gap because the top ring is very close to the land and runs hotter than the lower level of typical OE and OE replacement pistons. If the gap is less than the KB specified minimum, the ring ends may butt, which will break the piston crown, and this is more common than it should be because some "engine builders" don't follow the instructions and blame it on the pistons.

Maybe someone here or on the CF has experience fitting rings to KB pistons and can give you some guidance. Or check with local engine shops to see if you can get some guidance. In particular you don't want any burrs left that can scratch the cylinder walls.

Duke

[Dick W.]

Re: Sealed Power Piston Rings

Hi Mark... got your email. I've never filed a set of rings, but I believe you can buy "file to fit" sets, and I expect there may be a special file than needs to be used. It's very important to follow the KB instructions for minimum top ring gap because the top ring is very close to the land and runs hotter than the lower level of typical OE and OE replacement pistons. If the gap is less than the KB specified minimum, the ring ends may butt, which will break the piston crown, and this is more common than it should be because some "engine builders" don't follow the instructions and blame it on the pistons.

Maybe someone here or on the CF has experience fitting rings to KB pistons and can give you some guidance. Or check with local engine shops to see if you can get some guidance. In particular you don't want any burrs left that can scratch the cylinder walls.

Duke

I have used one of these for at least 50 years. I don't pay attention to how many turns it takes, I take time to check the ring in the bore often. The specs you quote are minimum clearances, a couple of thousands over is not going to be the end of the world.

[Duke W.]

Re: Sealed Power Piston Rings

I take it the photo is of a special tool used to file ring ends for greater gap...? How does it work?

Duke

[Dick W.]

Re: Sealed Power Piston Rings

I take it the photo is of a special tool used to file ring ends for greater gap...? How does it work?

Duke

Basically a rotary file. Place the ring on the platform, squeeze the gap together, and start cranking. It removes metal from both ends of the ring. Cut a little and measure often

[Joe L.]

Re: Sealed Power Piston Rings

I take it the photo is of a special tool used to file ring ends for greater gap...? How does it work?

Duke

Duke------


That tool is the ONLY way to do it. Using a hand held file is fraught with problems and "for the birds".

[Mark H.]

Re: Sealed Power Piston Rings

Basically a rotary file. Place the ring on the platform, squeeze the gap together, and start cranking. It removes metal from both ends of the ring. Cut a little and measure often

[Jim L.]

Re: Sealed Power Piston Rings

That’s it, though for a while I was trying to do one side at a time (sometimes I’m not very smart)

I don't see the need to file both ring ends. File just one end and the gap will increase. In fact, filing just one end is all I've ever done when assembling an engine for my vintage racer.

[Duke W.]

Re: Sealed Power Piston Rings

Basically a rotary file. Place the ring on the platform, squeeze the gap together, and start cranking. It removes metal from both ends of the ring. Cut a little and measure often

Very cool... never seen one before, but like I said earlier, I've never had to file a ring set.

I think Mark needs to borrow that from you for a few days. He lives in Virginia and is assembling a '64 Special 300 HP engine with KB pistons and the McCagh Special camshaft.

Duke

[Mark H.]

Re: Sealed Power Piston Rings

Very cool... never seen one before, but like I said earlier, I've never had to file a ring set.

I think Mark needs to borrow that from you for a few days. He lives in Virginia and is assembling a '64 Special 300 HP engine with KB pistons and the McCagh Special camshaft.

Duke

Ive got one - mine is from Summit Racing.



Just need to be better at using it properly!

Mark