One or Two piece piston oil control rings... Preference?

[john8662]

Well, i'm in the middle of putting the 6.2 together for the '86 and I was curious about the third ring set on pistons, being the oil control rings.

There are two designs that are used on the 6.2.

A Three piece oil control ring
-Top rail ring
-Center expander
-Bottom rail ring

and

A Two piece oil control ring
-larger oil ring/scraper
-center mounted "coil" expander.

According to my GM manual the two piece ring set was used on later model 6.2's to improve durability in high mileage engines (probably less oil consumption).

So whats the deal here?

I've got the three piece oil control ring set, was curious if I could have something better in there...

Comments?

Casey what did you use?

[More Power]

I specified the latest GM rings for the past two engine rebuilds I've been involved with. The first in late 1995 and then in late 1998. Once broken in, neither engines required a top off in 3000 miles (1/2 quart or so when using petroleum and 1/4 quart useage when running syn).

I don't know what style oil-control rings were used, other than what GM offered at the time.

Jim

[arveetek]

John,

I used the 2-piece design rings. They consisted of a coiled, spring-like ring that fit into the groove first, and then a large, one-piece ring that fit over the spring-like ring. They seemd to be a pretty good design. The inner spring-like ring had a wire that fit inbetween the gap that sealed them up really well, and made it like one solid ring after it was installed.

The reason I used these rings? It's what the Diesel Depot sent me! ;)

There were no brand markings on the box, so I'm not sure who made them. The pistons were stamped Mahle, but came in a Clevite box, and the rings were in an unmarked box, except for the part number.

Casey

On edit: if you use the two-piece design, be very, very careful when expanding them over the piston for installation. The large scraper ring is fragile, due to it's size, and is not very flexible. They can break rather easily....don't ask me how I know! :eek:

[john8662]

Thanks for the advice guys.

I'm ordering another set of rings for the 6.2 build. I'm confident that the two piece oil control ring is the way to go.

Thanks for the tip on the rings being fragile Casey, I'll just install them by hand or spiril them on verses using the ring expander as I would for the compression rings.

[arveetek]

Actually, John, you won't be able to spiral them on...they're too thick. Instead of two thin rings, it's one thick ring. Using the ring expander is probably the best way to install them. Just be patient and don't expand them any farther than necessary. Don't twist them.

I broke one when trying to remove it. I think it was the twisting motion that snapped it. If you will just open it straight out, and keep it all in the same level plane, you should be fine.

Casey