Ring Seating- What Actually Happens?

[oldkimmer]

This is how I have done mine for the last 44 years. Has always worked excellent for me. I learned this from an old timer. Kim

 

[mopar 3 B]

I'm about to get the pistons in the block so I've been contemplating ring gap position. I've got two engine building books, the instructions that came with the rings and the factory service manual. They all say something different! The FSM is rather vague, stating, "Be sure that the compression rings are staggered so that neither are in line with oil ring rail gaps. The oil ring expander ends should be positioned towards the outside V of the engine. The oil ring gaps should be positioned opposite each other and above the piston pin holes." I guess that's pretty exact for the oil rings. Use your imagination for the compression!!

 

[mopar 3 B]

I'm about to get the pistons in the block so I've been contemplating ring gap position. I've got two engine building books, the instructions that came with the rings and the factory service manual. They all say something different! The FSM is rather vague, stating, "Be sure that the compression rings are staggered so that neither are in line with oil ring rail gaps. The oil ring expander ends should be positioned towards the outside V of the engine. The oil ring gaps should be positioned opposite each other and above the piston pin holes." I guess that's pretty exact for the oil rings. Use your imagination for the compression!!

Most ring manufacturers use to put insulation instructions in the box. I have always followed the FSM.

Nothing hard about it. Ring expander towards the outside of block. Oil crappers opposite each other over piston pin. Compression pins not over oil crappers.
I put the first one 45° of the piston pin and the top one 180° front that.

 

[Cranky]

A good example of ring seating;
Race engine. Build it. Break cam in. Go straight to track and beat on it.
That's the best case scenario for modern rings.
And rings do rotate. Some high end guys actually have an rpm number for that.

If I wasn't going to the track right away with a street legal car, it usually got a good burnout in the street.

 

[RJRENTON]

What makes them rotate is the cross hatch. Kind of like gun rifling.

ABSOLUTELY CORRECT....the rings rotate in their respective lands due to the cross-hatching of the cylinder bore. These minute hone grooves retain enough of the oil film to provide lubrication. Rings can be "pinned" to prevent rotation but must be allowed to grow thermally or they will break. The exception may be a head land ring whose ends overlap to reduce blowby......just my opinion.....
BOB RENTON

 

[RemCharger]

ABSOLUTELY CORRECT....the rings rotate in their respective lands due to the cross-hatching of the cylinder bore. These minute hone grooves retain enough of the oil film to provide lubrication. Rings can be "pinned" to prevent rotation but must be allowed to grow thermally or they will break. The exception may be a head land ring whose ends overlap to reduce blowby......just my opinion.....
BOB RENTON

Bob I'm surprised that you didn't mention which engines are designed to require pinned rings. Are ya slippin'?

 

[RJRENTON]

Bob I'm surprised that you didn't mention which engines are designed to require pinned rings. Are ya slippin'?

Just getting older...perhaps forgetful. To rhat end, PLEASE enlighten me...always interested in learning more....
BOB RENTON

 

[not so famous bob]

In a nut shell, the face of the ring takes a set to the cylinder wall. Cast rings take longer than say a Moly filled ring and each one takes a different grit finish hone on the cylinders.

AGREE , mine took forever to seal , when they did , my engine vacuum jumped about 10'' ...

 

[rickseeman]

60 years ago you drove the car 500 miles to "seat the rings". In this process the rings were wearing down the "peaks" formed by the honing process eventually wearing these peaks down to Rk, their final position, and the rings are "seated". Then came engine builders with dynos. After building an engine they didn't want to run an engine 10 hours before they could get a real pull with seated rings. So I guess they are the ones that developed the process of plateau honing. After the normal honing process is over and you have the bore to size and the surface finish you want, you go to a fine stone, or what ever your preference is, and make a few light passes to knock the peaks off and get it down to the Rk that you want. Now you can put the engine on the dyno and make a full power pull without having to wait 10 hours. So on a modern race hone job you don't have to "break in" the engine to "seat the rings".