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carcrazy
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-- 05-08-2012 @ 9:38 AM
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Hi, I am assembling a V8-60 engine with .030" over NOS 3-ring cast alloy steel pistons. What is the best way to orient the piston ring gaps for best compression, least oil consumption and longest engine life? Thank you for any information you can provide.
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supereal
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-- 05-08-2012 @ 10:11 AM
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Be sure that the ring end gaps are correct, between .012 to .017, and that the top (compression ring) gap to groove side clearance is between .0015 to .0030. The rest of the rings side gaps is .0010 to .0025. The gaps should be staggered so no two are in line. Measure the end gaps by putting the rings about half way down the bore and level across the bore. This will help both compression and oil consumption. The cylinder walls should be honed enough to break any glaze and provide a visible pattern. This aids seating of the rings. Don't use synthetic oil until you have at least 500-1000 miles on the engine.
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Stroker
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-- 05-08-2012 @ 2:32 PM
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carcrazy: In addition to Super's excellent advice regarding gaps and break-in, I like to space the rings so the gaps are away from the thrust side of the bore (which is the top side on the left bank and on the bottom of the right bank)as viewed from the rear of the engine. I put the gap on the top ring at the bottom of the left bank, and the top of the left. The next (scr*per) ring I'd put facing either the front or rear of the engine, and the oil ring just the opposite of the scr*per. On a 4-ring piston, I'd put the bottom ring opposite the one above. The rings will probably move around a bit when you run it, but this is the way I like them to start out.
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keith oh
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-- 05-08-2012 @ 5:36 PM
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Dad,(A Ford Dealer in the 30s and 40s) Said he once asked that question at a Ford maintainance meeting in Detroit and was told it didn't make any differance, and they commented it would take as much time to do as they took to assemble the whole engine.
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Stroker
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-- 05-08-2012 @ 6:47 PM
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keith oh: I've heard the same thing, and I suppose there is a grain of truth to it, except that obviously lining up all the gaps will create a problem. I've taken many motors apart, and I'm sure the rings weren't where they were when it was assembled. I'm confident that they do move around some during use. That said, I was taught in the 50's by an old time rebuilder that the thrust side of the bore carries the greatest load, and that not having a gap there to start out was desireable.
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keith oh
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-- 05-09-2012 @ 8:57 AM
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Stroker,It sure isn't going to hurt to take the time to orient them as you suggest.
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FrankM-RG5
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-- 05-09-2012 @ 10:01 AM
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The Harley Davidson manual I used to rebuild a shovelhead years ago said the orient the ring gaps away from the thrust side and I believe the piston pin as well. I can't see how it would make a difference whether the gaps were aligned or not as pressure building between the two is going to leak. It is just a slightly longer path. It may be possible the piston is not supported quite as well as it gets towards the ring gap. That would make more sense to have them staggered. for the record I stagger the gaps and keep them off the thrust area. Definitely not hurting anything.
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