LS1 Piston rings
Thread Starter
Teching In
Joined: Sep 2025
Posts: 6
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From: North East Oklahoma
LS1 Piston rings Ive got an LS1 that's bored 0.030 over and I have pistons to match, but I can't find piston rings anywhere that will fit the overbore.
the pistons are from speed performance (PN: H868CP0.75MM) I checked there website and can't find a solid number to call and can't find the supposed piston rings they sell either. I plan on calling summit Monday to see what all they can help me with because that's where the so called pistons and rods were bought.
EDIT: I found some Hastings Piston rings that fit the piston and is the bore I need, but its the only set of piston rings I see online.
TLDR I need 0.030 over piston rings what all have you guys ran if you've bored it over?
the pistons are from speed performance (PN: H868CP0.75MM) I checked there website and can't find a solid number to call and can't find the supposed piston rings they sell either. I plan on calling summit Monday to see what all they can help me with because that's where the so called pistons and rods were bought.
EDIT: I found some Hastings Piston rings that fit the piston and is the bore I need, but its the only set of piston rings I see online.
TLDR I need 0.030 over piston rings what all have you guys ran if you've bored it over?
Last edited by Its38; Sep 6, 2025 at 11:35 PM.
12 Second Club
Joined: Dec 2017
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From: San Antonio
Agree with the rest; .030" oversize bore is a unicorn with a mermaid mother. If it is actually bored .030" over, I'll bet some patches of aluminum may be visible in some bores. It would be a very interesting discussion with the guy that bored it!!...
.030 overbore was the first thing that jumped out at me too. Are you sure that your talking about the LS1 block? Perhaps you meant to say .003. I haven't seen a 3.901 LS piston but I'm betting they're out there.
Last edited by 01CamaroSSTx; Sep 7, 2025 at 11:07 PM.
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They do make pistons that big as replacements that are sold in .12mm, .25mm, .50mm etc etc, but the machine shop needs to know better that it will not work. I take it they don't work on many LS? That block is now a paperweight.
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Joined: Jun 2016
Posts: 22,301
Likes: 3,625
From: Central Cal.
I'd be curious to know what those bores measure out to be as it looks to still have quite a bit of sleeve there. Have you measured to see if those pistons will go into the bore?
Ive got an LS1 that's bored 0.030 over and I have pistons to match, but I can't find piston rings anywhere that will fit the overbore.
the pistons are from speed performance (PN: H868CP0.75MM) I checked there website and can't find a solid number to call and can't find the supposed piston rings they sell either. I plan on calling summit Monday to see what all they can help me with because that's where the so called pistons and rods were bought.
EDIT: I found some Hastings Piston rings that fit the piston and is the bore I need, but its the only set of piston rings I see online.
TLDR I need 0.030 over piston rings what all have you guys ran if you've bored it over?
the pistons are from speed performance (PN: H868CP0.75MM) I checked there website and can't find a solid number to call and can't find the supposed piston rings they sell either. I plan on calling summit Monday to see what all they can help me with because that's where the so called pistons and rods were bought.
EDIT: I found some Hastings Piston rings that fit the piston and is the bore I need, but its the only set of piston rings I see online.
TLDR I need 0.030 over piston rings what all have you guys ran if you've bored it over?
Hastings Piston Ring Sets 2M5097010
I don't think the sleeve OD of a L33 is any different than a ls1 honestly on gen 3 stuff. I highly doubt GM had a sleeve that was a different OD based on extra parts/tooling. Back in the day it was common to open up a L33 to LS1 size sure, but not 0.030"-0.040" past that also.
I found a set, don't know who chanced a LS1 to go .030" over but there are Pistons out there for it.
https://www.jegs.com/i/Sealed-Power/...P75MM/10002/-1
Take it for what it's worth.
https://www.jegs.com/i/Sealed-Power/...P75MM/10002/-1
Take it for what it's worth.
Thread Starter
Teching In
Joined: Sep 2025
Posts: 6
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From: North East Oklahoma
I have fit the pistons into the block on to a crank without rings and they tap in just fine, personally I don't know what to thin piston walls would look like but they look fine on my end.
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Joined: Oct 2022
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From: Louisiana
I don't have the casting number wrote down anywhere easy for me to send, BUT I have looked it up it shows as an LS1 and the guy I bought it off of said it was out of a 2002 Firebird.
I have fit the pistons into the block on to a crank without rings and they tap in just fine, personally I don't know what to thin piston walls would look like but they look fine on my end.
I have fit the pistons into the block on to a crank without rings and they tap in just fine, personally I don't know what to thin piston walls would look like but they look fine on my end.