Reasons for rings not "Seating"
 

Hey guys,
So the new pistons will be on their way this week. The guy that is selling them to me said the reason he went with ross pistons is because the Rings on the mahle set did not seat properly due to too smooth of a bore. Have any of you heard of this? Also what does Seating really mean? I have heard this term many times before but never really paid attention to it.

Re: Reasons for rings not "Seating"
 

It means that the rings are holding up the proper compression in the cylinder and not allowing oil blowby in the crankcase, basically isolating the two to a degree. Mahle is a good piston, they've been around forever even supplying to exotic OEMs.

This topic has been beat to death here, but you want a decent 45 degree hone, use regular non-detergent oil for break-in, and follow the procedure of your choice. Ring and piston to wall gaps being correct should be a given.

Re: Reasons for rings not "Seating"
 

I would say the motorman/motoman break in method is best. Once you get it all installed take it straight to the dyno or beat on it!

Re: Reasons for rings not "Seating"
 

Yeah i know the break in methods by heart, but i was just wondering why a ring wouldnt seat, and what a properly seated ring is? Never heard of the cylinder wall being too smooth. And Steve you bring up a new term What is 45 Degree hone? I deglazed the cylinder with a plate style hone on the cylinder that had the bad piston.
Also when i install the pistons, should i use Oil or the Lubriplate lube on the walls? I was planning to use the luberiplate stuff on basically all metal to metal contact.

Re: Reasons for rings not "Seating"
 

too smooth?that might be an ra of 4 or 5 with a 5/64 cast ring.typical; finishes these days will have an ra[roughness average]of 8-15 or so with an 18 to 22 degree crosshatch angle,an rk of 20-25 rvk of 40 or less and rpk of 30 or less.point being that the days of backyard stuff are numbered and you will see more and more that just don't work anymore.ring technology has progressed to the point that your engine guy needs to know the type of ring [1/16 ,1.5mm,1mm,nitrided,stainless etc]and the vehicles intended use[na,blower,turbo,street,race]to correctly asess and apply the right wall finish for you.he needs to have good equipment and a profilometer or other device to measure wall finish or the odds of sucess get small...

Re: Reasons for rings not "Seating"
 

Every ring manufacturer has a specific hone pattern, but for the guy doing a hone at home, it's best to have approximately a 45 degree cross hatch pattern. I prefer the bottle brush hone since it makes the patterns easily with a variable speed drill on slow moving up the down the cylinder pretty quickly to get the 45 degree pattern.

Re: Reasons for rings not "Seating"
 

Use 30wt non-detergent oil. You want some metal to metal contact, that's what seats the rings. If you use some sort of assembly lube, the rings won't seat properly.

Re: Reasons for rings not "Seating"
 

Thanks for the info, been a big help. Looked at the hone i did and it looks approx 45 degrees. so i should be good. main reason i did the hone was to get out a small nick on the bottom of the cylinder so it didnt scratch up the piston skirts.
Should i hone the rest of the cylinders while i have all pistons out or just return them to their old locations and call it good?

Re: Reasons for rings not "Seating"
 

You don't want to re-hone the cylinders if your not replacing the rings. And you do want to hone it if you are replacing rings.

Re: Reasons for rings not "Seating"
 

make sure you final wash the block!! there is small grit particals left in the crosshatch that willglaze the bore or chew the rings up.

Re: Reasons for rings not "Seating"
 

That's what a clean rag soaked with oil is for, and an oil change after 20 miles, which you'd do anyways.

Re: Reasons for rings not "Seating"
 

if everything is cleand like it should be, then you will not need to change the oil at 20 miles
when you change the oil at 20 miles you remove the hi-pressure lube that was used.

I tell my customers, when I build there engine, to change the oil some where between 500-1000 miles, then run dino oil for 3000 more then they can swap to synthetic oil if they so choose too.

you can never get the inside of a block or the bores clean enough.

Re: Reasons for rings not "Seating"
 

crosshatch angles are important as the depth and angle,determine how much oil is retained on the walls and the rate of ring rotation.
not enough angle and the rings will rotate too slowly and not disapate heat properly,while leaving too much oil on the wall,allowing the rings to skip over the surface and cause oil consumption.
too steep on the crosshatch will not leave enough oil on the walls and can cause excessive ring rotation that will wear out rings and ring lands prematurely.
most manufactures specify a 22-32 degree angle, uniform in both directions.
can you hone your block at home?sure, but expect results comensurate with your methods.