I didn't say the rings were hammered into the ring grooves!!!
One of the piston companies, I'm thinking Arias or Venolia, made some pistons with top ring grooves that were ultra-tight in an attempt to aleviate ring flutter. The top ring groove was made the same width as the ring, .043, and the pistons were heated in boiling water to install the rings. While the piston was still hot, you put a compressor on the ring until the piston cooled off, and the ring was then held captive in the groove. When you fired the engine, the piston heated up, and the rings funtioned as normal, only with very tight clearance.
The reason I mentioned it is there is usually a reason for pistons sitting unused for long periods of time. For lack of a better term, I've used 'pressed fit rings' as one of those wierd things you don't want to find out about after you buy those bargain pistons. It's just one more of those things that were done that most people never heard of. And if you were to buy a set that were cut that way, they would be unuseable.
I'm thinking the close fit rings were tried in the late 60's or early 70's. Can't really remember for sure. I'm sure if you called Venolia or Arias, one of them could, maybe, remember such a thing if the person you talked to was old enough.
There have been a lot of things tried in the quest for HP that turned out not working or not worth the time and money. Close fit rings was probably one of them. Right now, we are going through the gapless ring marketing stage. And the Tornado Tube. ??? What will it be next? I'm still hearing talk of the "100 MPG" carburator. When you consider that the IC engine is only 20 to 30% efficient, and you consider how many BTU's are available in a pound of gas, you will quickly arrive at the conclusion that "100 MPG" out of a 3600 pound car is an unreasonable expectation. But the rumor keeps being spread by the unknowing.
Hey! There is another dyno test for DF. Find an old Fish carb and compare it to a modern FI. That should settle that argument once and for all!! Freiburger, I'm still waiting for my reply on the offset crank dyno test. I really think that with your pull, you should get Motown to cast a big block with offset cylinders. Then we could have a real apples and oranges test. (In the words of Daffy Duck:"I'd just like to see them try!")