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Author
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Topic: kb hyper pistons?
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the last dive
Gearhead Posts: 147
From: sydney australia
Registered: Dec 2001
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posted 04-19-2002 04:22 AM
  
has anybody ever broken a hyper piston in a 347? is this common? cause it looks like i have 1 broken,$$$$$$$$$$$$$$$$$$$$$$very unhappy
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67Coupster
Gearhead Posts: 189
From: Fortson, GA, USA
Registered: Oct 2001
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posted 04-19-2002 06:06 AM
Where did it break at? I run them in my 393W and so far so good. I have no intentions on using nitrous so I hope they will be ok. Only bad rap I've heard is when the top ring is not gapped per KB instructions.------------------
James
67 Coupe
393W, AFR 185, 4 Speed, 4.11 9 inch
7.09 @ 97MPH 1/8
1.55 60'
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 04-19-2002 09:38 AM
I have seen them break at the ring lands very rarely if the rings aren't gapped enough. The KB pistons don't absorb as much heat and don't expand like other pistons and the top rings tend to heat up more and need a little more gap . If this was the cause, you will need to add about .010" to your current top ring gap on all pistons. BS
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SteveLaRiviere
Administrator Posts: 45869
From: Saco, Maine
Registered: May 99
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posted 04-19-2002 09:45 AM
They are also said to shatter like glass under heavy detonation.------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
MCA Member # 47773 My wife says I don't pay enough attention to her... or something like that...
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Butch Jennings
Gearhead Posts: 633
From: No. California
Registered: Apr 2000
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posted 04-19-2002 12:29 PM
I've seen quite a few of them come apart in hard running street/strip cars, I've learned to think of them as an expensive cast piston. I won't use them at all, in a mild street/tow application I'll use a good cast piston and in any type of hot rod application I'll go forged. But then, I feel the same way about the cast steel cranks. I'll either go with a "quality ground" iron or jump up to forged steel....Just my 2-cents. ------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys"
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