I'm seeing a lot of serious misconceptions about cylinder prep and ring seating here, most of them "old mechanics' tales". That's the wrench jockey's version of an old wives' tale. Somebody who used to be a mechanic, or knew somebody who heard it from somebody else, starts repeating "facts" that just ain't so, and don't even make good nonsense.
Honing- - - - -that's a procedure done after boring, to remove the spiral groove left by the carbide cutter bit. It's done with a rigid-stone setup, and actually removes a couple of thousandths or more of cylinder material. It requires a thorough cleanup with hot, soapy water and a scrub brush, then repeated rinsing to get all traces of hone grit out of the block. This is best done with a totally disassembled engine- - -a bare block.
Glaze breaking- - - -done with various types of flexible-hone setups, either with three spring-loaded stones, or with a "dingleberry" hone consisting of dozens of ball-shaped pieces of grit on individual flexible stalks. Either way, it prepares the cylinder wall for a quick wear-in of a new ring set without reboring the cylinder. Virtually no material is removed by glaze breaking- - - -the surface of the cylinder just gets a crosshatch pattern without any diameter change. See above for cleanup procedures. The grit MUST be totally removed or the new rings wear out immediately.
Cylinder taper- - - - -this is wear that happens naturally over thousands of miles from the scuffing action of the rings. Practically all the taper in a worn engine happens in the first inch of ring travel. Even very high-mileage engines will show almost no taper wear from 2" below the top of the block to the bottom of the ring travel. Taper wear should not exceed .005" (5 thousandths) or the re-ring job will have a very short life due to ring flexing as the ring attempts to maintain contact with the tapered cylinder and it loses its springiness quickly.
Ring ridge- - - - -Unworn area at the top of the block from the rings not going all the way to the top. If a piston is forced out past a ridge, rings, or sometimes piston ring lands will be broken. If an engine has enough ring ridge to stop the piston from coming out of the cylinder easily, rebore the engine. You've got too much taper wear for a re-ring job. There are special reamers to remove the ridge if necessary. Always remove any ridge before installing new rings. A new ring will hit the ridge, and break the ring or the piston.
At 2,500 RPM, the rings in a taper-worn cylinder are trying to change diameter 5,000 times a minute to maintain cylinder wall contact. Reboring removes the taper, and allows rings to do their job for a much longer time without wearing out from metal fatigue.
Jerry
Last edited by Hotrod Lincoln; 12/17/2008 6:25 PM.
