Originally Posted by chasracer
And there you go again MouseFink. Do you have any idea of how many performance engines are built every week that have file-fit piston rings in them? And you think that makes them egg-shaped? Right.
Back to the questions......
Since you're going through all of this work to replace the rings to allow you to set the gaps where you want them, then I would purchase the .035 rings. There are a number of good write-ups, books and videos on performing this work if it is something that you have not done before. To me the biggest pieces of it are having a proper ring grinder. Stay away from the powered models, they're nice but not the best if you are new to this work. The hand powered ones allow you take off a little bit of the ring at a time and sorta sneak up on your preferred gap. Another piece is a method of squaring the ring in the cylinder accurately each time you check it. You don't want it down 1" one time and 3/4" the next. Last, a small file and sharpening stone to dress the edges of the cut ring. You don't want to leave an edge that's going to cut your cylinder walls.
Now Moly Rings. They are really good at sealing a cylinder and they break-in very quickly compared to the old chrome rings. The question in my head is what kind of hone pattern and finish did the block receive? Moly tends to prefer a smoother bore finish where as standard rings need something a bit rougher to help seat the ring. With the limited wear you have on the engine, the Moly might be dead perfect for it but I would check with your machinist.
Reason for my suggestion of forgetting about file-to-fit rings....this is a blown application, his gap requirement is going to be as big or bigger than regular out-of-the-box pre-gapped rings....with the file-to-fit it is more cost, and you just end up with 5 time as much ring to file away before the fit is correct.
I've run into the same thing on engines with a bigger than average nitrous hit planned(300+ hit). I'd imagine turbo builds to be the same way. For power adder applications, even a pre-gapped set will need some more gap files onto them.
If this was a naturally aspirated Super Stock or Stocker type engine or even a long life bracket engine where you would be looking for tighter gaps that you would get from a pre-gapped set then the file fits would be the better plan.