piston rings?

[Alan Roehrich]

About 6# tangential is what I have successfully run and had no oiling. with a Total Seal Napier cut second ring.

With 3/16" rings, my usual approach is to buy open stock Speed Pro SS50U oil rings, and use bore size rails with smaller bore size expanders.

Unfortunately, Speed Pro has been bought several times over the last decade or so. They've become less and less oriented toward customer service and open stock sales, also, I've been told that as the SS50U tooling wears out, they're not going to repair or replace it. In my experience, the Speed Pro SS50U oil ring is the finest in design and quality, as well as the most friendly to the machinist, builder, and assembler.

The expander in the SS50U is what controls ring tension, and the radial width of the rail is consistent and stable, as well as easy to assemble. Not so with the Hastings/Perfect Circle oil ring with the gold expander. In near 40 years of doing this, I've never had a problem, or a customer with a problem with the SS50U. Not true at all with the Hasting/Perfect Circle.

As far as testing tension goes, my method is similar to many others. I oil the cylinder with the oil to be used when the engine is being raced, carefully wiping it until it is wet, but not completely slathered in oil. I install the piston with the oil ring only into the bore, with a pin in the piston, and the pin connected to a 0-12# scale. I then roll the engine inverted, and pull the piston from the deck toward the crankcase, and record the drag.