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Max bore size for 4.505 file fit rings #2757359
03/29/20 07:14 PM
03/29/20 07:14 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline OP
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I just measured the end gap in my megablock with new unfilled Total Seal 4.505 rings. My bore is now 4.5043 so I was wondering how much more room there would be before the rings would have too much end gap.
With a new 4.505 ring measured in the 4.5043 bore the end gap was .010. Using .0225 as a proper end gap for NA apps, that would allow a bore of 4.5082 and still be at .0225 end gap. I am not sure what effect the extra crevice volume would have on an alky motor, but if it isn't too much , coating pistons to take up all that extra bore space would allow a lot of rehones and rerings. It cost me $300 to have line2line coat my pistons. That is a it cheaper than a rebore and new pistons!

Last edited by gregsdart; 03/29/20 07:18 PM.

8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: Max bore size for 4.505 file fit rings [Re: gregsdart] #2757437
03/29/20 11:07 PM
03/29/20 11:07 PM
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dvw Offline
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Simple math, ring gap grows .0031416" for every .001" increase in bore size.
Doug

Last edited by dvw; 03/30/20 08:22 PM. Reason: reword
Re: Max bore size for 4.505 file fit rings [Re: dvw] #2757506
03/30/20 09:22 AM
03/30/20 09:22 AM
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challenger1320 Offline
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I think you missed a 0 should be .003

Re: Max bore size for 4.505 file fit rings [Re: challenger1320] #2757511
03/30/20 09:53 AM
03/30/20 09:53 AM
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gregsdart Offline OP
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To figure max bore size, I had too little end gap at .010 ( which I have to file to .0225 for 4.5043) of .0125. Divide that by Pi, or 3.1416 and you get. .03915 that the bore can increase before the rings get too small to allow the .0225 end gap I want for the top ring. Line2line doesn't directly claim any power increases for the skirt coatings, but just tightening up the piston to wall clearance might help some. With the freshen up and extra 22 cubes plus .6 of a point compression increase I hope to see 15 to 20 hp anyway. We will see when I finally get this thing screwed together and the tracks are open.


8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: Max bore size for 4.505 file fit rings [Re: gregsdart] #2757526
03/30/20 10:35 AM
03/30/20 10:35 AM
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rickseeman Offline
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I have used 4.500" file-to-fit rings (which are really 4.505" rings as it says on the box) on 4.505" pistons. This naturally works fine. Not as much to file, and some might have a few thou extra end gap but everything will work fine.


2011 Drag Pak Challenger
Re: Max bore size for 4.505 file fit rings [Re: gregsdart] #2757549
03/30/20 11:22 AM
03/30/20 11:22 AM
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Shelby Twp. Mi
HardcoreB Offline
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Originally Posted by gregsdart
I just measured the end gap in my megablock with new unfilled Total Seal 4.505 rings. My bore is now 4.5043 so I was wondering how much more room there would be before the rings would have too much end gap.
With a new 4.505 ring measured in the 4.5043 bore the end gap was .010. Using .0225 as a proper end gap for NA apps, that would allow a bore of 4.5082 and still be at .0225 end gap. I am not sure what effect the extra crevice volume would have on an alky motor, but if it isn't too much , coating pistons to take up all that extra bore space would allow a lot of rehones and rerings. It cost me $300 to have line2line coat my pistons. That is a it cheaper than a rebore and new pistons!

I may be wrong because of alcohol but .0225" may be a touch on the tight side for end gap on the top ring. How far down is the top ring groove from the crown? Doug, what gap did you use on your top???

Re: Max bore size for 4.505 file fit rings [Re: HardcoreB] #2757628
03/30/20 03:00 PM
03/30/20 03:00 PM
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Sidney,Ohio
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challenger1320 Offline
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https://www.omnicalculator.com/math/circumference
Here is a calculator to help you out. But you are correct on your numbers.

Re: Max bore size for 4.505 file fit rings [Re: HardcoreB] #2757758
03/30/20 08:27 PM
03/30/20 08:27 PM
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dvw Offline
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Originally Posted by HardcoreB
[quote=gregsdart]I just measured the end gap in my megablock Doug, what gap did you use on your top???



Fixed my fat finger post above, .0031416" Looked up my ring gaps .026" top, .028" 2nd oil .015" Bore is 4.505"
Doug

Last edited by dvw; 03/30/20 08:28 PM.
Re: Max bore size for 4.505 file fit rings [Re: dvw] #2757806
03/30/20 10:07 PM
03/30/20 10:07 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline OP
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Doug, i will have to check mine too as well as look over the old rings for any problems. I thought i set them up at .005 per inch of bore on the top and .026 2nd, but memory is possibly wrong.


8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: Max bore size for 4.505 file fit rings [Re: gregsdart] #2757974
03/31/20 12:21 PM
03/31/20 12:21 PM
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dthemi Offline
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multiply both bore sizes by 3.141 then subtract one number from the other. THat will be the difference in gap

so your difference is .0022

Re: Max bore size for 4.505 file fit rings [Re: gregsdart] #2758028
03/31/20 02:46 PM
03/31/20 02:46 PM
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Cab_Burge Offline
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I use the .0045 per inch of bore formula on the top ring and add .002 to .004 more for the second rings, IE 4.375 bore = .001968 so I open it up to at least .020, .024 to .028 on the second ring up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Max bore size for 4.505 file fit rings [Re: Cab_Burge] #2758077
03/31/20 05:04 PM
03/31/20 05:04 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline OP
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Total Seal says .0045 per inch of bore for gas, alky , e85. Doug it sounds like a bigger gap isn't hurting your performance at all with the gets you run. Which brings?me to the statement on the box; if you have had good luck with another gap size than recomended, go with the bigger of the two. Lots of variables can affect the minimum gap required.


8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: Max bore size for 4.505 file fit rings [Re: gregsdart] #2758128
03/31/20 07:31 PM
03/31/20 07:31 PM
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dvw Offline
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Think about it. Hypothetically if the dimension they but at is say .020". If you gap them .025" the running gap is .005". My bet is .005" means squat. Now if they but? We're talking failure.
Doug







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