5.3 Ring gap
Feb 15, 2015 | 12:48 PM
#1
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5.3 Ring gap
I've got an L33 that I'm rebuilding. Keeping stock crank and rods, put a set of sealed power pistons in because the stock ones had wear on the skirts. Anyways... I bought the appropriate rings for them P/N E-937K
The rings came and are separated within the package. They are also identified by where the bevel is at on the inside. The installation instructions don't say anything about checking gap.
I obviously checked the gap, and on the first 2 (top and middle) and the top ring gap was .020 and the second was .014.
Now this goes against everything I've researched and what I learned in school. It's a mild NA 5.3 (3.780 bore) so .004x3.780 = .015 and the second should be about 20% larger so .018..
Why are these rings backwards? I've checked multiple rings in multiple cylinders and they are all about the same.
Dug out the old pistons and rings and measured those. .031 on top and second rings. I can't find the GM sepc for ring gap for a 5.3 either, only LS1
The rings came and are separated within the package. They are also identified by where the bevel is at on the inside. The installation instructions don't say anything about checking gap.
I obviously checked the gap, and on the first 2 (top and middle) and the top ring gap was .020 and the second was .014.
Now this goes against everything I've researched and what I learned in school. It's a mild NA 5.3 (3.780 bore) so .004x3.780 = .015 and the second should be about 20% larger so .018..
Why are these rings backwards? I've checked multiple rings in multiple cylinders and they are all about the same.
Dug out the old pistons and rings and measured those. .031 on top and second rings. I can't find the GM sepc for ring gap for a 5.3 either, only LS1
Last edited by SupaDupaSteve; Feb 15, 2015 at 04:39 PM.
Feb 15, 2015 | 02:53 PM
#2
Formerly ScreamingL
Joined: Oct 2003
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From: From the 412
tore down many stock motors and never once found a 2nd ring to be less then top, 2nd ring has been around .022 and .025 from what ive experienced and the top ring was around .014-.018
sure youre not backwards
sure youre not backwards
Feb 15, 2015 | 04:33 PM
#3
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110% sure they aren't backwards. dot facing up per the instructions that came with them
Feb 17, 2015 | 12:04 PM
#4
Sure you don't have top and 2nd ring mixed up? I do think that .014" is too tight for a hyper piston like that. If the ring end-butts it'll tear the piston apart. I'd call tech help and confirm which ring goes where. If you can't get it sorted I'd send them back or exchange them.
the latest thinking is that the 2nd ring should have the same or a bit larger gap than the top ring. Production gaps may be a bit looser to just prevent ring endgap butting in any case. Tighter ring gaps are for max effort N/A. Too tight is worse than too loose, so I'm not surprised that stock parts would be on the loose side.
I used a set of Mahle rings in my 5.3, and the top ring came in about .016" and the second ring was about .018". I did have to file fit a couple of them to increase gap a thousand or two, but nothing like what you're seeing. I agree with your calculations, but I can't explain the measurements.
the latest thinking is that the 2nd ring should have the same or a bit larger gap than the top ring. Production gaps may be a bit looser to just prevent ring endgap butting in any case. Tighter ring gaps are for max effort N/A. Too tight is worse than too loose, so I'm not surprised that stock parts would be on the loose side.
I used a set of Mahle rings in my 5.3, and the top ring came in about .016" and the second ring was about .018". I did have to file fit a couple of them to increase gap a thousand or two, but nothing like what you're seeing. I agree with your calculations, but I can't explain the measurements.
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