Gapless Piston Rings
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Northstar Engines and System Technical Discussion Discussion, Gapless Piston Rings in Cadillac Engine Technical Discussion; I bought a 99 STS with 120 miles with a leaking head gasket. I ordered the stainless head gaskets and ...
  1. #1
    Loose screw is offline Cadillac Owners Fanatic
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    Gapless Piston Rings

    I bought a 99 STS with 120 miles with a leaking head gasket. I ordered the stainless head gaskets and am currently doing the stud conversion (not cheap). The Cylinders look great as do the rings but as I am in there and spending this kind of money I want to replace the rings and of course the rod bearings. But having searched the messages I can not find much about GAP-LESS piston rings on N* engines or specific parts recommended.

    Are Gap-less rings recommended? If so or not, could you please supply Part numbers and source and why you recommend the rings you do.

    I also need the same for Rod Bearings and new Rod Bolts.
    Having spun a rod bearing in another N* engine I want to make sure I install only the best.

    Please - part numbers, source and why. Thank you

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  3. #2
    Submariner409's Avatar
    Submariner409 is online now If it won't run, slap in a big stereo
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    Re: Gapless Piston Rings

    Call the guys at www.chrfab.com

    But look at their disclaimer down under the engine picture: You're looking for engine parts which do not exist. At 120,000 you never should have disassembled the lower end unless the oil pan or halfcase seals were leaking badly.

    For all parts other than the head gaskets and Jake's studs, use the most common online GM/Cadillac references in here and Seville.

  4. #3
    Ranger's Avatar
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    Re: Gapless Piston Rings

    Are you saying that you already pulled the pistons? If so, that's too bad. Lower end never needs work.

    What's a gapless ring? How do you install it?

  5. #4
    Submariner409's Avatar
    Submariner409 is online now If it won't run, slap in a big stereo
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    Re: Gapless Piston Rings

    "Gapless" rings have an overlap, or step, at the gap - they aren't "gapless" per se - they are supposed to have less low speed leakdown, but the OP doesn't realize that the Northstar uses special low-tension rings with a computer-controlled cylinder hone and leakdown is not a problem. The cylinder pattern should be visible after over 200,000 miles: it's also an oil control crosshatch design. The only change is that 2003+ replacement pistons use a coated skirt to minimize scuffing from the newer oils with less ZDDP. Also, the crank uses special journal fillets, and the GM service manual cautions not to grind the crank - replace it if the journal specs fall outside the .002" undersize bearing replacement.

    He posted that he wanted part numbers and sources, so advice appears useless.

  6. #5
    Loose screw is offline Cadillac Owners Fanatic
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    Re: Gapless Piston Rings

    Yes pistons pulled. The last N* I worked on a 94 concourse I was glade I pulled the pistons, the rings were seriously worn due to oil starvation but the cylinders looked great but the engine still ran well and was not burning oil which could have changed soon.

    allot of discussion here about Gap-less rings but I didn't see anything specific about use in Northstars: http://www.speedtalk.com/forum/viewt...hp?f=1&t=18568

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    Ranger's Avatar
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    Re: Gapless Piston Rings

    Quote Originally Posted by Loose screw View Post
    Yes pistons pulled. The last N* I worked on a 94 concourse I was glade I pulled the pistons, the rings were seriously worn due to oil starvation but the cylinders looked great but the engine still ran well and was not burning oil which could have changed soon.

    allot of discussion here about Gap-less rings but I didn't see anything specific about use in Northstars: http://www.speedtalk.com/forum/viewt...hp?f=1&t=18568
    That's rare.

  8. #7
    tateos's Avatar
    tateos is offline Cadillac Owners Connoisseur
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    Re: Gapless Piston Rings

    Loose screw:

    All really good info Ranger and Sub - they are telling you straight.

    Nevertheless, you are going to do what you want to do, and we wish you well.

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