Ring Gap - How loose is too loose

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Dec 22, 2010 | 04:48 PM

TWG

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Ring Gap - How loose is too loose

First time rebuild here. I picked up a 99 LS1 that was allegedly rebuilt w/ new rings/bearings/gaskets/etc. Don't have any specs (Manufacturer unknown) for the rings, but after a minimal hone (Machinist says .0005), I'm trying to re-use the rings that came with the motor.

Trouble is, they are all fairly consistent at .023/.028 (Top/Bottom). Bore is STD, plus the hone (3.8985?), so I'm definitely loose over the general recommendation of .015/.020.

Motor is going to be carbeurated, and going into a low-mileage '70 Chevelle, with a 100 shot on top. It is a stock rebuild, re-using all stock parts. Am I clear to continue, or do I need new rings. If so, any rec's on a part #?

Second ring example:

-TWG

Last edited by TWG; Dec 22, 2010 at 05:24 PM.

Dec 22, 2010 | 06:23 PM

O2Form

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PISTON RINGS:
Top Comp. Thickness: 1.500mm / 0.59"
Top Comp. Gap Clocking: None Required
Top Comp. End Gap (P): 0.23-0.38mm / 0.009-0.0149"
Top Comp. End Gap (SL): 0.23-0.38mm / 0.009-0.0149" Max.
Top Comp. Groove (P):0.04-0.085mm / 0.00157-0.003346"
Top Comp. Groove (SL):0.04-0.085mm/0.00157-0.003346"Max.
2nd Comp. Thickness: 1.500mm / 0.59"
Top Comp Gap Clocking: None Required
2nd Comp. End Gap (P): 0.44-0.64mm / 0.0173-0.0251"
2nd Comp. End gap (SL): 0.44-0.64mm / 0.0173-0.0251" Max.
2nd Comp. Groove (P): 0.04-0.08mm / 0.00157-0.003149"
2nd Comp. Groove (SL):0.04-0.08mm/0.00157-0.003149"Max.
Oil Cont. Rail Thickness (2): 3.00mm / .188" (EACH)
Oil Cont. Top Rail Gap Clocking: 25 degrees from Top Ring
Oil Cont. 2nd Rail gap Clocking: 25 degrees from Expander
Oil Cont. End Gap (P): 0.18-0.69mm / 0.007-0.0271"
Oil Cont. End Gap (SL): 0.18-0.69mm / 0.007-0.0271" Max.
Oil Cont. Groove (P): 0.01-0.22mm / 0.0004-0.00866"
Oil Cont. Groove (SL):0.01-0.22mm / 0.0004-0.00866" Max.

Dec 22, 2010 | 06:45 PM

TWG

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Quote:

Originally Posted by O2Form

Right...I got that I'm out of specs by roughly +.007/+.003. My question hinges on how much this matters on a low-mileage street car w/ some nitrous. Is it worth the ~$170 for new rings?

Dec 22, 2010 | 07:08 PM

O2Form

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Second ring gap is ok...just the 1st you need to tighten up....

Dec 22, 2010 | 11:11 PM

hiltsy855

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From: Iowa

Did the motor run after the re-build? If it did then re-using rings is a non-no anyway. Adding .0005 to the bore would only increase the end gap a little less than .002.

Dec 23, 2010 | 08:26 AM

speedtigger

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From: Florida

Most guys run a little looser top ring end gap with nitrous. For exact specs for your application, contact the ring manufacturer and they can tell you. This is an important step because different ring materials can expand at a different rate.