440 ring gap

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Darthemi75

Darthemi75

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I bouth a set of kb237 flat top hypereutectic pistones for my 440 .030

Original Chrysler Manual says .013-.023 ring gap but i dont know what is the best for a street car.

Whats your recommended ring gap for first, second and third rings.

Thanks
 
what does the instructions say that come with the pistons or the rings...?
 
Depends on what you're doing but you should lose the manual for those pistons. On the top ring if you read the instructions they should say something to the effect of .0055" per inch of bore for low rpm/stock, .0075 per inch of bore for performance street/tow, and .0085 per inch of bore for race/NOS. You really need to read the paperwork and use the spec that covers the most abuse it will see. If you plan to race it at all, use the race spec. For the second ring you can use .005 per inch of bore, plus .005. The oil ring should not need filing, just make sure the ends of the expander butt properly.
 
most rings are .004 - .005 per inch of bore size, but some of the modern rings are much tighter, and if you are a NOS user you need to be on the loose side.

I woul give them a call, but the .025 .028 for top sounds right, and .023- .026 for 2nd. But call to make sure.
 
everyone please note...KB hyper pistons do not take the same ring gaps as normal pistons due...

the top ring is higher up on the piston and must use a larger gap or you will butt the ends and ruin the engine...

READ the Instructions for KB hyper pistons...
 
70aarcuda said:
everyone please note...KB hyper pistons do not take the same ring gaps as normal pistons due...

the top ring is higher up on the piston and must use a larger gap or you will butt the ends and ruin the engine...

READ the Instructions for KB hyper pistons...
Click to expand...

he is right. you better set them to the kb specs. unless you like tearing the engine down again. i have the kb107's in my 360, & the rings are set to the kb specs. 300 + passes, no problems.
 
Dart,
Answerrring as instructed....lol

First.. the link to the KB site's chart http://kb-silvolite.com/clearance_pop.php

Second.. as for the reason the 2nd gap should be larger... The way rings work is this: top ring is the compression ring. It's designed to seal against the walls and on the up-stroke it seals on the lands of the piston in order to seal in the gases. We talk about cylinder wall finish but using a good piston means the best sealing surface for the ring too. The second ring is not a compression sealing ring, but rather an oil scraper by design. It's not coated, and is has more of an edge to it that isnt good at sealing gases. But it does remove the last remnants of oil from the walls on the down stroke. The third ring is the main oil control ring. The issue with the 2nd ring gap comes when there is oil being removed from the walls, and it prevents the escape of gasses that get traped between the top and 2nd rings. Once that happens, the top ring is pushed up off the ring land, losing a good part of it's sealing. The fix is to simply enlarge the end gap on that 2nd ring. It is fairly common to have this problem so it can really help especially above 3-4K rpm. So use the guide for the top ring, then for the 2nd ring.... but then add about .005" to that 2nd ring number. It usually ends up around .022-.024".
 
moper said:
Dart,
Answerrring as instructed....lol

First.. the link to the KB site's chart http://kb-silvolite.com/clearance_pop.php

Second.. as for the reason the 2nd gap should be larger... The way rings work is this: top ring is the compression ring. It's designed to seal against the walls and on the up-stroke it seals on the lands of the piston in order to seal in the gases. We talk about cylinder wall finish but using a good piston means the best sealing surface for the ring too. The second ring is not a compression sealing ring, but rather an oil scraper by design. It's not coated, and is has more of an edge to it that isnt good at sealing gases. But it does remove the last remnants of oil from the walls on the down stroke. The third ring is the main oil control ring. The issue with the 2nd ring gap comes when there is oil being removed from the walls, and it prevents the escape of gasses that get traped between the top and 2nd rings. Once that happens, the top ring is pushed up off the ring land, losing a good part of it's sealing. The fix is to simply enlarge the end gap on that 2nd ring. It is fairly common to have this problem so it can really help especially above 3-4K rpm. So use the guide for the top ring, then for the 2nd ring.... but then add about .005" to that 2nd ring number. It usually ends up around .022-.024".
Click to expand...


So.. to resume all the posts:
1 ring gap: 28"
2 ring gap : 22"
3 oil ring: ????
I only want a street restoration car.
 
Right On Moper, KBs run all the way into the deck HOT area. 2nd ring creates a vacumn slows down piston, ADD NOS add clearance
 
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