Teach me about rings

[Car #4]

The Ring Gap Questions thread makes me realize how little I know about rings. So I take it that the ring gap is the space between the two ends of the ring. How do you adjust? Aren’t the rings preformed?
If the job of the ring is to seal between the piston and the cylinder wall then doesn’t it have to have proper contact against the wall. In my mind the ring comes preformed to provide the proper tension against the cylinder wall to create a seal between the wall and the piston. Then you compress the ring into its groove in the piston to install the piston.
Also, don’t the rings each have a different name and purpose? My memory is a little fuzzy. Grade 9 auto shop class was a long time ago.

 

[69L48Z27]

The ring is preformed and has the correct tension. The end gaps are fit for the application. Some will come out of the box ready to go and others are considered file fit due to thermal expansion. Power adders create more heat, and need more clearance. You have to adjust the ring gaps so they don’t butt into one another and create damage when everything is hot. Too tight of a ring gap will destroy the ring land and tear the top of the piston off, further destroying the cylinder. Stock applications will have rings available that don’t need anything done but you always check your gaps at assembly time.

 

[Cranky]

Also thinner rings has less drag and produce lower temps. Gotta have pistons made for thin rings.....cannot install thin rings on pistons made for thicker ones. There's a ton of info on the net about just rings or at least there used to be.

 

[HawkRod]

The general rule is that you need a MINIMUM of .004" per inch of bore. So a 4.000" bore needs at least .016" gap. As @69L48Z27 said, if you are really making horsepower, you need to increase that even further.
The second ring should be gapped at least as much as the Primary ring, with perhaps a thou or two more. Old school wisdom was that the second ring should be gapped smaller, but they found that blowby from the first ring could actually cause problems with the primary ring due to pressure between the rings.

Interestingly, rings are one the primary causes of drag and load on your engine. Common ring sizes are 1/16". NASCAR now uses very thin rings (IIRC .5mm). These rings, believe it or not, hold up better than the old, larger rings. I think as time goes on we will see thinner and thinner rings.

 

[WileERobby]

This ring ?

 

[turbine68rt]

Remember to clock the end gaps so they don't line up during assembly.

 

[RemCharger]

And rings rotate. Not that it reeeeally matters to us much.

 

[Cranky]

And rings rotate. Not that it reeeeally matters to us much.

I've heard that from way back but never charted any. Seems the engines I tore down weren't built by me and the ones that were built by me weren't torn down by me. There's one engine here that I built for myself that hasn't been fired but didn't chart the rings and not about to pull a head off off to do that because by the time it'll need to be worked on again....I'll most likely be gone lol

 

[RemCharger]

I've heard that from way back but never charted any. Seems the engines I tore down weren't built by me and the ones that were built by me weren't torn down by me. There's one engine here that I built for myself that hasn't been fired but didn't chart the rings and not about to pull a head off off to do that because by the time it'll need to be worked on again....I'll most likely be gone lol

Ya there's no need to pop your heads on and off to check ring position.. if they aren't spinning you'll know. She'll be an oil burner.
Iirc they figure it's about 20-40 rpm.

 

[1 Wild R/T]

Well, there's the Engagement Ring.... The Wedding Ring.... And the Suffer Ring... Oh, wait... Wrong Rings.... Sorry Sorry..

 

[Cranky]

Well, there's the Engagement Ring.... The Wedding Ring.... And the Suffer Ring... Oh, wait... Wrong Rings.... Sorry Sorry..

Is a Suffer ring the same as a Nose ring? Axin fer a feind....

 

[1 Wild R/T]

Is a Suffer ring the same as a Nose ring? Axin fer a feind....

 

[WileERobby]

Well, there's the Engagement Ring.... The Wedding Ring.... And the Suffer Ring... Oh, wait... Wrong Rings.... Sorry Sorry..

...or these rings ?