12-02-2018, 02:03 AM
Hi Bob and all,
I met with an experienced engine builder this morning (about another issue) and asked for his opinion. It looks to RR and Ruaridah were on the right track.
When I built the engine the advice I got was that, if there were dots on the rings then the dots face up, if there were no dots and just marks (mine had .030" marks), then the marks go up, if no marks and not dots then do as you please. Well it seems that this mantra is only partially correct. If there are dots then, dots face up, but the other marks are meaningless in terms of orientation. My rings have an external chamfer (opposite side to the 30" markings) and these must face down and I had them facing up.
It makes sense now that it's been explained to me. If the chamfer is facing up it acts as a face for the expanding gas to act against and compress the ring thus pulling it off the cylinder face.
I went back and checked the old rings, no dots or chamfers but it’s very conceivable that the chamfer had been worn away as the ring gaps were along way out of spec when I stripped it down.
Thanks for all your input, will let you know how it goes when I get it back together in a few weeks. But feel free to keep the ideas coming.
I met with an experienced engine builder this morning (about another issue) and asked for his opinion. It looks to RR and Ruaridah were on the right track.
When I built the engine the advice I got was that, if there were dots on the rings then the dots face up, if there were no dots and just marks (mine had .030" marks), then the marks go up, if no marks and not dots then do as you please. Well it seems that this mantra is only partially correct. If there are dots then, dots face up, but the other marks are meaningless in terms of orientation. My rings have an external chamfer (opposite side to the 30" markings) and these must face down and I had them facing up.
It makes sense now that it's been explained to me. If the chamfer is facing up it acts as a face for the expanding gas to act against and compress the ring thus pulling it off the cylinder face.
I went back and checked the old rings, no dots or chamfers but it’s very conceivable that the chamfer had been worn away as the ring gaps were along way out of spec when I stripped it down.
Thanks for all your input, will let you know how it goes when I get it back together in a few weeks. But feel free to keep the ideas coming.