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Discussion Starter #1
Anyone have experience with gapless rings? Im thinking to buy a new set of rings and machine the 1st ring from the outside bottom to fit a thin ring (maybe the oil ring) on it and align them opposite with 180 degree.
 

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I have run gapless rings on some of my engines with excellent results. But the cost to effect ratio is high. I have rebuilt many engines, some real cheaply and a few $15,000 rebuilds making 1000++ Horsepower. Every turbo or supercharged engine I have help rebuild has had gapless rings. A few ultra high output non turboed engines also got gapless rings. When a set of standard type rings are running $200, a gapless set are $400-$600. Not worth the cost on most street run engines. Race/street engine maybe but for all out race engines, for sure. So for a AN200/AN400/AN650 I do not know if the gain would be worth it.

I did a non turboed 11.25:1 compression Chrysler (Dodge Shelby) 2.2L with 1mm over chrome faced iron rings. I had the end gaps on the tight side of the spec's for my pistons and a proper 45 degree hone pattern for the rings. After seating the rings in, I had a fare amount of blow-by leakage and about 185 PSI on a compression meter. I then lightly re-honed the cylinders and I mean lightly just clean the glazing off, installed the gapless rings, ran it to seat the new rings and had so little blow-by and my reading went from 185 PSI to 215 PSI. After I had over 30,000 miles on this engine I did another compression test and had between 215 and 220 PSI. My oil stayed cleaner longer too.

The top iron ring is machined with a stepped grove all around the outside diameter. That step is about 2/3's the rings width and just a bit more deeper than the thin oil ring you will use, like 0.0025 to allow some oil to get trapped between the two rings. The oil ring inside diameter is also machined off to fit inside the top iron's grove with also about 0.0025 clearance for oil and some movement. And yes face the two gaps 180 degrees apart.

But now the OIL that you use must be VERY good and changed often or the two rings will carbon up and cause problems. The 3000 to 5000 mile oil change interval will still work but I would use a synthetic oil and change the filter every time too. No 7000 mile oil changes like most of us do when running synthetic oils.
 

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Discussion Starter #3 (Edited)
Thank you Dave, that's exactly how i was thinking, 2/3 of the 1st ring width will be machined from the bottom outside diameter.
Do you recommend the 2nd ring to be gapless as well? Or it will prevent lubricant to the 1st ring?
 

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Only one ring needs to be done. On some engines the second ring is the one to do but I can not remember why. I always did first ring.

A lot of information is here: Totalseal Gapless Rings
 

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Discussion Starter #5
Maybe when the first ring is thinner, then the second ring will be easier to work on.
 
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