Piston Ring gap

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Waco Demon

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I'm building a 340 for my 72 Demon with Sealed Power Moly rings . The engine is boared out to 020 over , the compression ring gap is .025 , my Dodge book , betweem .010 and .020 . Any coment ?
Waco Demon
 
what pistons are you using?....

I am assuming that you have 5/64 width rings...

you can buy file to fit rings.....rings are .005 larger then the bore and then you file to fit your ring gap...
 
I always use file-to-fit rings... If you're using stock replacement pistons stock rings are fine. If you are running a performance piston then you should get file-to-fits. A basic spec for ring gaps is .004" per inch of bore for top ring(non hypereutectic piston) and .006 for the second ring, always rounding up to the next whole number. So your 4.06 bore would need on top ring: 4.06x.004=.0162 rounded to .017... Second ring 4.06x.006=.0243 rounded to .025. You will need to file fit the stock type ring for these specs.
 
70aarcuda I have Speed Pro pistons and yes I'm talking about the 5/16 ring . We inserted the ring in the cylinder bore about 1/2 " down and mearured the gap it was .025 . The Dodge manual , the ring gap should be between .010 and .020 . Waco Demon
 
see moper comment...that is what your ring gap should be...

are you using a ring squaring tool to square the rings in the bore before you measure the gap...
 
you two choices...

live with the ring gap of .025 or buy file to fit rings...
 
Did you verify that bore size? It sounds like the bores are too large. You can verify it with a vernier caliper and measure the pistons too...
 
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