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Re: Piston to head clearance
[Re: DusterKid]
#2540832
08/24/18 12:00 PM
08/24/18 12:00 PM
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Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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Somewhat dependent on bore size and chamber shape, but after .060" the knock suppression is weak, at .100" it's about gone.
Boffin Emeritus
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Re: Piston to head clearance
[Re: dogdays]
#2540984
08/24/18 06:16 PM
08/24/18 06:16 PM
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Joined: Jan 2005
Posts: 4,243 Charlotte, North Carolina
sgcuda
master
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master
Joined: Jan 2005
Posts: 4,243
Charlotte, North Carolina
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The effect still works in the roller 318s which have something like 0.080 piston to head clearance. No it doesn't. Working over the years, in a Chrysler dealership, there have been numerous software updates and half a$$ed fixes for 5.2's and 5.9's with spark knock issues. Maybe a thinner head gasket would have been a better fix.
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Re: Piston to head clearance
[Re: DusterKid]
#2541070
08/24/18 10:58 PM
08/24/18 10:58 PM
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Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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P-H is 2 different issues: quench (knock suppression) has a limited range of effectiveness, with a small bore and plug near the exhaust valve you may not need to be really tight - Jenkins reported minor pumping gains in a non-critical SBC by going up to .060". This may also be true of alcohol engines where high comp is safer. Squish is the turbulence and mixture homogenization caused by mixture being expelled from the tighter space and (if you're lucky) aimed at the plug - this is generally helpful even if very loose.
Boffin Emeritus
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Re: Piston to head clearance
[Re: polyspheric]
#2541096
08/25/18 12:35 AM
08/25/18 12:35 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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My take: measured carefully (piston rock) I want .040"
live every 24 hour block of time like it's your last day on earth
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