So, the Hastings doc says on page 8, stagger the gaps 180 degrees. And it says on page 11, a one directional cut (vs crosshatch) will cause excessive ring rotation. I'm not arguing whether they rotate or not. I guess you either believe it or not. I will say that using the argument that the crosshatch pattern in the hone job causes the rings to rotate makes one wonder if the crosshatch is done right, will they ever rotate? The rotational forces would counteract each other. Just sayin'... Thanks for all the input. I'll come up with something and write it down this time so I don't forget again. Dan
Yes we always oppose the gaps when installing rings...... But ....they rotate... Period.... Here's another example of proof.... In stroker and long rod engines it's not uncommon to have a support rail for the oil ring...... Because of pin location.... You'll notice a dimple in the rail...... In the days before the dimple I've seen the gap of the support rail find its way over pin bore.... Even though it was installed skirt side..... And I've seen oil rails and expanders wound through that gap as well..... Sorry no pic of that Here ...at rebuild time....on a used piston you can see where the dimple has worn its way on both sides of the ring land over the pin bore.....the support rails DO NOT touch the cylinder wall,and have enough tension on the radial depth of the piston that they should not move.... Yet the oil ring can drag it around when it's rotating....or moving back and forth....point is they dont stay still..... Now...want to think harder? What do you think that a roller valve spring with 250 lbs on the seat and 6-700 lbs open does at rpm? Would you believe it lifts off the spring seat in the head when the valve closes? Think your stock springs wont do that as well? Posted using the Full Custom H.A.M.B. App!
No matter the method of honing, the final stroke leaves the prominent spiral pattern which will promote slight ring rotation in the piston ring groove. Plateau honing can reduce this phenomenon.
I was watching this thread unfold from the sidelines...was going to put my 2 cents in, but tfeverfred's avatar distracted me also. Bottom line is if you say the rings don't rotate, but Smokey Yunick says they do....you lose. .
Oh wow, I think that I remember her name to be Candy Barr. What a good girl! Hastings says that the oil ring expander is to be installed with the butting ends up and not overlapped. The 2 oil rings should be at 180 degrees.
"Piston Rings | 37 1.6.11 Piston ring movements Ring rotation in order for piston rings to run-in and seal properly, they must be able to rotate freely in their grooves. The ring rotation is the result of the honing pattern (cross grinding) on the one hand, and the rocking movement of the piston at the top and bottom dead centre on the other hand. flatter honing angles cause fewer ring rotations whereas steeper angles result in higher ring revolution rates. The ring rotation also depends on the engine speed. 5 to 15 revolutions per minute are realistic figures to get an idea of the dimension of the ring rotation. on two-stroke engines, the rings are secured against rotation. As a result, both ring rotation and rebounding of the joint ends into the gas channels are prevented. Two-stroke engines are mainly used in motorcycles, gardening machines and the like. The irregular wear of the rings, a possible coking in the ring grooves and a restricted service life due to inhibited ring rotation is tolerated in this regard. in any case, this type of application is dimensioned for a shorter service life of the engine from the outset. The requirements made on a normal four- stroke vehicle engine that is in road use, are higher by far where the mileage is concerned. The twisting of the ring joints by 120 ° to each other is only intended for facilitating the start of the new engine. After this period, any conceivable position of the piston ring inside the ring groove is possible, provided the rotation is not inhibited by design (two-stroke engines),"
The Jalopy Journal
