To bore or not to bore Lc9 5.3
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Teching In
Joined: Aug 2023
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From: Oklahoma
To bore or not to bore Lc9 5.3 Ok im doing a basic refresh on my LC9 and deleteing AFM etc. Im a little worried about cylinder taper, but less so after doing some research here.
I have been measuring my cylinders but have not yet honed them. Trying to decide weather to bore it out or not. The measurement is consistently within 1 thou to 1.5 thou with the exception of 1 cylinder that is 3.5 thou out of round at 1" from deck. Mine is a 5.3 so a bore of 3.780 and I'm measuring 3.7865 to 3.788 at 1" down and half way down and at the bottom of bore. Meausred 90° at all levels so 6 numbers per cylinder. There is not much taper at all and not much our of round. The only question I have after reading some post is if 6 to 8 thou cylinder wear is too much for stock rings and pistons. I realize it will change when the head are torqued down and after honing. But would that little bit need to be bored? Or just hone and call it good with the stock pistons and new rings?
I have been measuring my cylinders but have not yet honed them. Trying to decide weather to bore it out or not. The measurement is consistently within 1 thou to 1.5 thou with the exception of 1 cylinder that is 3.5 thou out of round at 1" from deck. Mine is a 5.3 so a bore of 3.780 and I'm measuring 3.7865 to 3.788 at 1" down and half way down and at the bottom of bore. Meausred 90° at all levels so 6 numbers per cylinder. There is not much taper at all and not much our of round. The only question I have after reading some post is if 6 to 8 thou cylinder wear is too much for stock rings and pistons. I realize it will change when the head are torqued down and after honing. But would that little bit need to be bored? Or just hone and call it good with the stock pistons and new rings?
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Joined: Dec 2017
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From: San Antonio
With it that close, I wouldn't bore it. A little flex hone to clean it up would be fine. I hear that the LC9 can be bored to 3.898". I've never tried it, but increasing displacement to the LS1 size would be the only reason to bore it.
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Teching In
Joined: Aug 2023
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From: Oklahoma
Yeah it's in my wife's suburban so I'm not spending a ton on it if I can avoid it. Lolit it has 255k miles on it and was burning oil and leaking oil like crazy and I'm amazed the AFM hasn't messed up in it. Initially I just wanted to do thw AFM delete but the cam bearings were worn badly so I pulled it to fix oil leaks and install all new bearings and rings.
12 Second Club
Joined: Dec 2017
Posts: 1,034
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From: San Antonio
Yeah, with that many miles, it's time to freshen things up. You might as well do a full rebuild. I would just clean the pistons, and put new rings on them. The LS7 spec lifters are a good choice. Throw in a little truck cam, and you're good for another 250k miles.
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From: Oklahoma
That is exactly the plan
