Very interesting question.
First i do not know what make of piston rings i use. It's a chrome top one, a cast middle and a 1 piece oil control. It comes in an dirty , ex piston or whatever what's lying there box from my machine shop. They know i want quality parts and i think they take from different types/makes rings to make a set as i do not like the 3 piece oil control ring. These are not cheap as for a sprint set i have to pay about 150 euro. BUT, in my former 260.000km use and abuse dolomite engine i had about 0,5 liter oil consumpsion á 10.000km at the end. They are good. I can ask what make it is but i do not think it's a set because they can order seperate rings at size and not as an engineset.
It is a reliable machineshop that does what you ask. Not own minded. The good thing is they are very cheap for machining for me because all the overhauling of my work goes there also.
For example last year i had an classic Ferrari v12 with oval piston holes and small ends. Cylinders and pistons on size, nothing wrong but i think an assembly fault of the former owner/machineshop in the past. Pistons are about 350GPB x12
Called them if they had a solution and they ordered 12 piston pins from a suzuki alto á 8gpb a piece. They had the same dimensions but were .15mm thicker so a little bit of roaming in the pistons and small ends and all ok again. I like the thinking of this shop.
As for the gap, i think it has to do with expanding. The only way the rings go is up and down in the groove and with angled gaps they are pushed away sideway's and starting to turn in the grooves?
Jeroen
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Classic Kabelboom Company. For all your wiring needs.
http://www.classickabelboomcompany.com
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). I alway's modify the reverse casting piece what's on the rail. I hate pulling a lever so it goes in without pulling. Just machine it angled and about 2mm higher than 3/4. This way it does not accidentally goes in reverse but pushing right it goes in, like most modern cars.
