AndyGT
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| posted on 23/2/17 at 09:02 PM |
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piston rings
Just been looking at this guide to fitting new piston rings:
www.duncanracing.com/TechCenter/4strk_ringinstall2-24-05.pdf
The rings I bought suggested using the wedge sided compression ring in the middle with "TOP" pointing up and a square edged compression
ring as a top compression ring with manufacturers writing pointing up but the above link says the opposite!! : "wedged" ring to top of
engine and squared to middle
Who is right? 
If the rings were fitted incorrect (i.e. middle to top and top to middle), what would the consequences be?
btw, this is on a (c)20XE engine.
nothing is impossible
everything is possible
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r1_pete
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| posted on 23/2/17 at 09:19 PM |
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That guide reads as for assembling motorcycle engines, last paragraph talks about sliding cylinders onto pistons, and makes no reference to using a
ring compressor to facilitate fitting pistons into bores.
Go with the instructions on your rings, they should come individually packes with their location and orientation on the piston clearly marked, the
only thing in that article of relavence is the 120 degree spacing of the gaps, which also need checking against manufacturers spec.
[Edited on 24/2/17 by r1_pete]
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perksy
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| posted on 23/2/17 at 10:12 PM |
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Follow the instructions from the manufacturer of the rings, you won't go far wrong
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Slimy38
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| posted on 24/2/17 at 07:33 AM |
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quote:
Originally posted by r1_pete
, the only thing in that article of relavence is the 120 degree spacing of the gaps, which also need checking against manufacturers spec.
I seem to remember reading somewhere that spacing is largely irrelevant as piston rings rotate and settle in a completely random position. It might be
good practice to start with them evenly distributed but it's not essential.
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r1_pete
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| posted on 24/2/17 at 10:39 AM |
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Yes Ive read that too, But as you say starting at 120 is seen as best practice.
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chillis
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| posted on 24/2/17 at 10:44 AM |
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The 'wedge' shaped ring usually goes at the top as it is the 'ridge dodger' If these rings are being fitted in a freshly
rebored cylinder then where the ridge goes doesn't matter, Indeed I would put the wedge in the middle on a fresh bore but it must go at the top
for a 'used' bore that has only been glaze busted or the top ring will break first time you run it.
[Edited on 24/2/17 by chillis]
Never under estimate the ingenuity of an idiot!
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