The Stovebolt Site Forums The Shop Area Engine Shop piston ring orientation

I have searched here and referenced my various motors manuals and I cannot find the ring orientation on a 235 6.
If memory serves me right the oil ring gap is inline with the pin with the upper and lower 30 degrees off of that with the compression rings 90 and 90 degrees from that over the skirt, is this right

Hy Dune, I have never actually seen a piston ring orientation drawing for a 235 or most old engines for that mater. I was taught that you don't place any ring gaps on the thrust sides of the pistons, 90 degrees from the piston pins, and to place all gaps 180 degrees apart, there are other ways to do this of course, but these general rules have always served me well, hope that helps.

Ring gaps orientated 120 degrees apart at least for 1954 high pressure 235/261.

Ring gap orientation makes absolutely no difference, as long as you don't align them straight above each other- - - - -and even if you do, they won't stay that way long. I've got a glass-cylinder engine I use for training purposes, and with a timing light pointed at the cylinder, I can watch the rings rotate around the piston. Rings are constantly in motion, so even if the gaps line up momentarily, the pressure leakage is minuscule. At 2,000 RPM, the individual compression and power strokes happen 17 times PER SECOND! Not much time to get a pressure leak!
Jerry

I realize that it doesn't make a whole lot of difference, but I am surprised that Chev gave a spec. I don't think GMC addresses the subject. Either that or I just overlook it.

Ring gap orientation makes absolutely no difference, as long as you don't align them straight above each other

Yup - they're supersonic hula-hoops after the engine starts.

WOW, I'd sure like to see that motor with a glass cylinder. Can you tell me a little more about that?
Thanks, Doug

We have two of them at the high school where I teach, single-cylinder overhead valve engines, with permanently lubricated Torrington bearings at both ends of the connecting rod and the main bearing positions, so the crankcase is open to view- - - -no oil. The cylinder is tempered glass, with a plastic shield around it in case it gets overheated and shatters- - - -which is possible, I guess, but unlikely. For extended runs, I can connect an air hose and blow air around the cylinder for cooling. One of these engines has been there since 1970, and gets run regularly. I run it on alcohol, gasoline, Propane, natural gas, lacquer thinner, and just about anything else combustible. I can "Freeze" the piston in just about any position, top to bottom, by using a delay-flash timing light. The engine is made by a company called "Megatech" which makes training aids for school shops.
Jerry

crenwelge,

My GMC Maintenance Manual does not directly address the issue but says to follow the ring manufacturer's installation instructions. Some manufactures give detailed instructions on ring orientation. Others state to just not line up the gaps - and that less than 5% of total ring "leakage" might ever come from properly gapped rings.