On Wednesday 02 August 2017 10:16:13 R.L. Wurdack wrote: > > -- > > > > > ------------------------------------------------------------------ > > >------------ > > > > Check out the vibrant tech community on one of the world's most > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > Pardon my confusion: > > 1. Are you talking about honing the cylinder before inserting the > sleeve? > > 2. Gene, bu 'ring gap' do you mena the slot clearance for the ring or > the distance between rings? > > TNX, > > R.
The distance between the ends of the ring when placed into the cylinder and a piston is used to push it square to the bore. Check the gap between the ends of the ring at various places from top to bottom of the bore. The minimum must be maintained at any position of the stroke The ring needs room to thermally expand w/o this gap closing else it will bind tight, temps from friction will quickly hit a damage the bore, the rings spring will go away or the pistons grooves if this occurs. Ring gap minimums are generally listed someplace in the replacement ring kits, and varies some dependent on the rings order on the piston, with the top ring needing more clearance because its hotter. Higher performance engines, think those 3 second top fuel dragsters, might have an 1/8" gap! If a feeler blade of that gap size won't fit, then obviously the ring should be removed and the ends filed to open up that gap until the feeler blade will fit. A bit sloppy doesn't hurt. Dikes pattern rings will, for obvious reason of the upper lip often being flush with the top of the piston, are closer to the fire and need a larger gap, as will the thin (20 to 30 thou thick) steel rings used in the higher performance 2 stroke engines. I've no clue if that ring style is being used in the modern, 40+ mpg and pollution reducing engines today, but its definitely in the bag of tricks as its maybe 10% of the running friction of a conventional ring, having very little at rest pressure against the cylinder wall, with gas pressure supplying nearly all the sealing pressure. Raising its position on the piston reduces the pockets of unburned gases, and reduces the pollutants generated, so its a net plus all around. And I read a promo in the early days claiming they could work at piston speeds considerable above the 4000 FPM that usually breaks the conventional cast iron ring into 1/4" long pieces. Personally BTDT in the larger late '40's Nash Ambassador engine. I turned one of them I had tuned up quite a bit, close to 8500 revs in low overdrive one evening showing a loudmouthed 51 ford driver how its done while dragging 2 blocks for the titles. With that engines long stroke, that was well north of 4000 FPM. To those not familiar with the Dikes Pattern term, the ring isn't a square cross section but a thin L shape, with the piston groove being just wide enough to accept the bottom of the L, and the piston turned down enough above this groove for room for the leg of the L sticking up. Compression and combustion pressure gets behind the L's inside face and supply's 95% of the rings pressure against the cylinder wall to effect the gas seal. Engines built that way can often be turned over by a single hand on the fan belt. Very low friction. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
