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surfshark 09-21-2006 07:17 PM

Seeking 383 chevy ring gap specs
This seems to be something of a preference type of question because I have gotten different responses from my machinist, as well as tech lines I have called.

I was checking my ring gaps for a .030 over 383 I'm building (my first), and the top rings gapped at .014 (with one at .013) each, and the second rings gapped at an even .020 each.

These are Speed Pro rings part # R-8902-30. The top ring is chrome moly and the pistons are forged 10.5(approx) Speed Pros.

My machinist told me that .014 is fine if I'm not running nitrous, and that they will open some more after so many miles are on the engine. I plan for it to be a decently strong street engine. He recommended not to go any lower than .012 on the top rings.

The tech lines I called gave me a figure of no lower than .018 on the top rings. The other tech line told me .004 (huh?).

My machinist has the best reputation in town here and I tend to prefer to go with his advice, but I'm wondering if I should just file the rings up a thousandth or so to about .016 which he recommended in case nitrous might be in the engine's future. I sure appreciate any advice. Thanks.

nitro_baller4692 09-21-2006 07:21 PM

i would go with .016'' so you have some versatility if you choose to run nitrous.

surfshark 09-21-2006 07:25 PM

Thank you for the advice. Right now I don't plan on nitrous, but I never know what I would want later on.

If I can ask another question: What is the proper method for filing chrome moly rings? I understand that I have to be careful of the moly coating while I file.

Thanks again.

nitro_baller4692 09-21-2006 07:34 PM

there is a tool,speedway motors sells them for $34.95
this is the best way to gap rings and for the money it's a great tool to have if you plan to build more then one engine in your life time. :thumbup:
part #91089408

surfshark 09-21-2006 07:37 PM

Thanks, I will get one. Even if this motor flies apart, I plan to keep trying.

nitro_baller4692 09-21-2006 07:51 PM

thats the spirit,all but the flying apart
sometimes parts do fail though :smash:
anymore questions will be here to make sure it stays together.
best of luck with your build.

IanRiordan 09-22-2006 05:18 AM

I'm guessing the second tech line meant .004" per inch of bore diameter - a common measure for top rings ( .016" in your case).

T-bucket23 09-22-2006 07:10 AM

I have a question, why does nitros require a wider ring gap.

RPMs 09-22-2006 07:23 AM

no2 requires a bigger gap because of high temps in the cyl. This causes the ring to grow more. .004" per in of bore is pretty much a standard spec. So .014"-.016" would be great. And .016-.018 in a nitrous motor.

Be sure to get all the burrs of the ring after you file it. You also want to cut the ring from the outside edge toward the center so as not to chip or round of that outer edge that will go against the cyl wall.

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