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01-10-2022, 06:53 PM | #21 | |
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Re: piston ring end gap spacing ?
Quote:
Which auto engines have the rod installed after the piston is inserted? As far as why rings rotate, maybe temperature changes as the engine warms up? Not sure, but let me relate what I saw years ago. I was cleaning the muffler on an old chainsaw and started it with the muffler off. At BDC the ring was visible in the exhaust port so with the engine running it appeared to be motionless. Running at part throttle I could see the ring gap moving. The gap would appear at one side of the exhaust port, then move across the port and disappear. It did this several times a minute. Visible proof that rings rotate! |
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01-10-2022, 06:58 PM | #22 |
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Re: piston ring end gap spacing ?
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01-10-2022, 07:16 PM | #23 |
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Re: piston ring end gap spacing ?
The main reason I know of that some pistons pin the rings is so 2 cycle engine ring ends do not cross the port.
Some engines are taken apart very often. I find the rings as I installed them. I can't remember one I've taken apart that didn't have the gaps spaced enough. |
01-11-2022, 11:16 AM | #24 | |
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Re: piston ring end gap spacing ?
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YMMV
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01-11-2022, 02:36 PM | #25 |
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Re: piston ring end gap spacing ?
You better hope that the gap never closes! If it does, ring expansion puts a tremendous load on the cylinder wall, causing the ring to weld itself to the wall and bad things WILL happen! There has to be at least a little gap which, if the ring never rotates, will leave a tiny unworn spot on the wall.
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01-12-2022, 11:44 AM | #26 | |
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Re: piston ring end gap spacing ?
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01-12-2022, 03:51 PM | #27 | |
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Re: piston ring end gap spacing ?
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Bill |
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01-12-2022, 05:36 PM | #28 |
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Re: piston ring end gap spacing ?
"Gapless" rings are not truly gapless. Otherwise, how could you get them on the piston?? They are two piece rings with a gap. One piece is thin like an oil ring rail and the main part of the ring has a groove to accommodate the thin piece. The gaps are to be installed 180 deg. apart but it's reported that the gaps are sometimes lined up on disassembly. I read of a "labyrinth" ring used on Geo Metros but whatever that is, you still have to get it over the piston to install.
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01-12-2022, 08:28 PM | #29 |
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Re: piston ring end gap spacing ?
Apart from the wear issue, does the ring gaps aligned cause any compression loss in that cylinder? I say no, what do others say?
John |
01-12-2022, 09:15 PM | #30 |
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Re: piston ring end gap spacing ?
The piston ring manufacturers recommend staggering them at installation. Maybe it's only an issue for a brief period during the first few minutes of operation, or during break-in, to help guard against possible cylinder glazing? No idea, but if it's all the same I still like to read and follow the instructions when I can.
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01-12-2022, 11:58 PM | #31 |
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Re: piston ring end gap spacing ?
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