| Poster |
Message |
 fasttoomas
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 RING END GAP SMALL BLOCK 383
All greetings.
I on such question.
Who knows what there should be a backlash at piston rings?
At me 2 books and in them are written on a miscellaneous.
In one book it is specified a backlash of the top ring 0,016-0,018 backlash of the second ring 0,022-0,024
and to another the book it is written that a backlash of the bottom ring 0,010-0,012
WHAT the VARIANT CORRECT?
Thanks.
Variant 1
RING END GAP RECOMMENDATION GUIDE (FOR 4.000 INCH BORE)
Speed Pro Top Rings
(ductile iron, 4" bore) 4.000" Example Minimum Gap Factor
Moderate Performance .016 - .018 (.004 per inch of bore diameter)
Drag Racing, Oval Track .018 - .020 (.0045 per inch of bore diameter)
Nitrous Oxide - Street .020 - .022 (.005 per inch of bore diameter)
Nitrous Oxide - Drag .028 - .030 (.007 per inch of bore diameter)
Supercharged .024 - .026 (.006 per inch of bore diameter)
Speed Pro 2nd Rings
(cast Iron, 4" bore) 4.000" Example Minimum Gap Factor
Moderate Performance .020 - .022 (.005 per inch of bore diameter)
Drag Racing, Oval Track .022 - .024 (.0055 per inch of bore diameter)
Nitrous Oxide - Street .024 - .026 (.006 per inch of bore diameter)
Nitrous Oxide - Drag .028 - .030 (.007 per inch of bore diameter)
Supercharged .024 - .026 (.006 per inch of bore diameter)
Variant 2
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| 24.03.2008 at 08:45 |
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partel
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RING END GAP SMALL BLOCK 383
Hey!
383 is 4.030 bore, not 4.000
Too small gap is a problem:
quote:
One of the persistent problems we encounter is piston ring end gaps that are too small. Many racers are squeezing the end gaps in order to improve leakdown test results. Well, if you want to see zero leakage on your meter, just put O-rings on your pistons. But if you want to make power where it counts - on the race track - you must have enough clearance to prevent the ends of the piston rings from butting under actual operating conditions. Even if you don't reach the point of damaging the cylinder walls, you risk impairing the ring seal if the end gaps are too small. In our Pro Stock engines, we run generous .028-inch gaps on the top rings. Believe me, if I thought there was power in tighter end gaps, I'd reduce the clearance in a heartbeat.
http://rehermorrison.com/techTalk/29b.htm
And if the second ring gap is too small, the gas pressure will lift the top ring and break cylinder seal.
This is also good:
http://rehermorrison.com/techTalk/22.htm
And other David's articles are good, too...
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| 24.03.2008 at 09:30 |
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fasttoomas
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RING END GAP SMALL BLOCK 383
Thank you for quick answer.
Beside me pistons 4,060 sizes.
The speech goes In article about motor of the high power, beside them clearances little others.
But I collect modest stroker. |
| 24.03.2008 at 14:42 |
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jyrki
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RING END GAP SMALL BLOCK 383
The theories concerning ring end gaps have changed some in the past few years. In the past, they used wider top ring gaps than in the second ring. Today, the trend is to open the second ring gap a little bigger than the top.
The goal of course is to keep the pressure in the chamber side, and not in the oil pan and out of the breathers. When warm in a running enigne, a proper end gap will expand the rings so that the gap will be pretty close to zero. There is also special zero gap rings in at least a couple of configurations, that provide almost complete seal of the cylinder.
The piston style also has an effect on the required ring end gap, for example in hypereutectic pistons the top rings tend to run way hotter than in other piston styles, and require a bigger gap.
I really wouldn't be too concerned about the exactly "correct" ring end gaps. When people didn't yet realize that the second ring gap should be bigger than the top, the engine run too, and some of them run even extremely well. In most cases this kind of things aren't what will, or will not, make the engine run well.
The top ring does about 90% of the compression sealing, so that's what is most important. According todays theories, a too small end gap in the second ring may trap gases between teh top & second ring, and cause the top ring to flutter causing excessive blow by. I have never had this happen with regular rings, but have seen two cases where this happened with zero gap rings, both at very high rpm. It was a thing that will not go unnoticed blowing out the oil gaskets, valley baffles etc.
With a round cylinder honed with a honing plate, and small ring end gaps, you may see leak down of maybe 5%. With zero gap style rings , it isn't uncommon to even have 0% leak down. Now, if you open the ring end gap a little, and end up having for example 15% leak down, don't except to gain any power by fixing that up to the 0-5% range. The most important thing is that you have enough ring end gap. The worst thign that can happen is with too little ring end gap, the rings expanding because of heat, and the ends butting. The resulting sight isn't usually pretty. A little more than needed is way better, than little less than needed.
PS, according to my old Direct Connection engine bible, "a ring end gap of .014"-.016" is adequate for the top ring and .004" less for the second. Do not in any case exceed a gap of .018". It worked back then, and it will work now. Unless you have to be HIFI.  |
| 26.03.2008 at 10:31 |
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partel
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RING END GAP SMALL BLOCK 383
Hey Jyrki, good to see master @ work 
Fasttoomas, pay very close attention, Jyrki is the best.
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| 27.03.2008 at 03:40 |
1 edit. Last edited 27.03.2008 at 03:49 by partel
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fasttoomas
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RING END GAP SMALL BLOCK 383
Thanks big jyrki .
I have correctly understood the theory?
top ring .014"-.016"~ 0.35mm-0.40mm
second 4.060X0.004=0,01624 ~0.41mm
At present after my gaugings my top ring makes 0.37mm(0.014"), and the second 0.45mm(0.017"). Then it turns out that, and to change them it is not necessary.
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| 27.03.2008 at 05:27 |
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jyrki
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RING END GAP SMALL BLOCK 383
That should work fine with regular cast or forged pistons in a naturaly aspirated gasoline engine. With hypereutectics, the top ring end gap should be opened close to 0.7mm, the factor is 0.065" x 1" of bore diameter. |
| 28.03.2008 at 11:33 |
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fasttoomas
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RING END GAP SMALL BLOCK 383
I asked this question to firm which is engaged in assembly of motors in the USA. Here that, they have answered me.
Hallo fasttoomas,
If it's a Speed-Pro piston you will want the TOP RING at .018 to ..020. You don't need the extra gap with Speed-Pro pistons. The 2nd ring will remain the same. Thanks, Ted.
Hallo fasttoomas,
KB Piston recommends your TOP ring end gap needs to be .026". The second ring end gap doesn't require a special setting .014 to .018 will be fine. Thanks, Ted. |
| 28.03.2008 at 14:35 |
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