Ring gap

Discussion in 'PSI Superchargers Tech Questions' started by craig moss, Dec 7, 2009.

  1. craig moss

    craig moss Member

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    I have a bbc 12:1 40 psi boost alc. 4.560 bore, hell fire rings what is the min. top ring gap?( was thinking .030 ) This is a boat wet block/heads.The cylinders have a max water temp. of 95 deg. min. 60 deg. water going to them. Also has anyone ever had a engine apart after break in and checked how much the gap changed? Thanks Craig
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    #1
    craig moss, Dec 7, 2009
  2. SoDak

    SoDak Active Member

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    I always use what the mfg recommends for end gap.

    I have a motor apart right now that has 2 runs on it since brand new, I'll could check it but I sure don't expect its changed at all.
     
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    SoDak, Dec 7, 2009
  3. Ken Sitko

    Ken Sitko Super Comp

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    I run .040 on my top rings, .032 on the 2nd ring, in a 4.310 bore. Years ago I tried running .024 to .030 on the top ring, but they butted up hard and scored the cylinder. Look at your manufacturer's recommended gap, I would think it would be .040 or more.
     
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    Ken Sitko, Dec 7, 2009
  4. Mike Canter

    Mike Canter Top Dragster
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    Craig, thanks for your PM.

    According to Speed-Pro those Hellfire rings for the top and second ring gap are both the same at .006 times the bore spacing. So that is .02736 or .028" gap on both. They gap the second ring at the same as the top to avoid ring flutter and premote better sealing
     
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    Mike Canter, Dec 7, 2009
  5. WANNABE

    WANNABE New Member

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    Well, lets get back to a point at hand. This is a boat. And what do we know about boats. That the bore of the block never increases as much as if it were in a car, because the unlimited supply of cold water does not let the block grow. So we put an extra thou to thou and a half in the bore of the block (piston to wall) for that. Don't forget to add that in with the ring manufacturers recommendations. And also, a little too lose loses a very small amount of power, but butting the rings is the end.
     
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    WANNABE, Dec 8, 2009
  6. Brian Carpenter

    Brian Carpenter Member

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    I would never run .030..too tight .036-.040 should be ok but every app. is different. Just keep an eye on it at tear downs. Better to be loose than too tight. Just my .02
     
    #6
    Brian Carpenter, Dec 8, 2009
  7. secondwindracing

    secondwindracing top alcohol

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    It floats:D
     
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    secondwindracing, Dec 8, 2009
  8. Mike Canter

    Mike Canter Top Dragster
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    Like to discuss ring gap if some are willing. Maybe all get some good info.

    Let me start off by saying what I have found out over the years and tell me if I am wrong or is there some additional data.

    As far as what I have been told by Barry Botnick who was a factory rep for Speed-Pro and talking to Childs and Ackerly that the gap of the rings are dependent on sveral items:
    1. The bore diameter. Being that a gap on a 4.00 bore can't be the same as a gap on a 4.50 bore and still different from a 4.60 bore.
    2. The amount of heat being generated in a motor. A race tuned nitrous motor heats the rings more than a blown alcohol motor. Actually Speed-Pro divides it up into five catagories based on heat generated in the combustion chamber.
    3. And lastly the type of material the rings are made from because each type of ring has a different expansion characteristics from heat. A tool steel ring expands at a differently than a stainless steel ring or a tempered ductile iron alloy.

    Just for info..the Childs and Ackerly Xtreme rings are identical to a Speed-Pro Hellfire ring and made by the same company which I believe is Hastings. There are only two main ring manufacturing companies.
     
    #8
    Mike Canter, Dec 9, 2009
  9. Ken Sitko

    Ken Sitko Super Comp

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    Mike, when I ran my hellfire piston rings in a 526 inch blown hemi, I first started out with .032 on the top ring and .024 on the second ring. It didn't take long before all the cylinders were scored all the way around, which ruined the pistons and the sleeves. If you tried to turn the motor over immediately after the run, it was very tight, once it cooled off it was back to normal. I know we were probably too lean, but I didn't want that to happen again.

    To solve my problem, I talked to a couple of fast guys, who told me they wouldn't run any less than 40 on the top ring, and slightly less on the 2nd. I have been running with these specs ever since, and had no problems.
     
    #9
    Ken Sitko, Dec 10, 2009
  10. aj481x

    aj481x Member

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    I will just throw this in for whatever it's worth. We just finished some hard dyno pulls on a BAE 521, gaps were .022" top and second. Looked perfect after tear down. Put them back in. SP Hellfires.
     
    #10
    aj481x, Dec 10, 2009
  11. Mike Canter

    Mike Canter Top Dragster
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    Ken, you know what might have happen is that they put the wrong rings in the box. I have had that happen to me once about four or five years ago on a set of Sealed-Pro Hellfires. They didn't look like some I had sitting around so I called thenm up and described them to them and they sent me a new set that looked good. Also those dabs of color coded paint was different on them what ever that means. The reason I say this is we have used Hellfire and Xtreme rings in big nitrous motors and blown alcohol motors and have always gapped them at .006 time the bore and have checked them for rubbing after a while and have never had a problem.
     
    #11
    Mike Canter, Dec 10, 2009

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