Piston Ring Port Sizing

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JKreider
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Location: Redlands, CA

Piston Ring Port Sizing

Post by JKreider » Tue Sep 03, 2019 8:07 am

Has anyone come across any standard for the maximum port size (along the circumference of the ring) that cast iron piston rings can slide over without danger of scuffing the ring and/or port, based on ring OD and thickness?

Jim Kreider
Last edited by Harold_V on Wed Sep 04, 2019 1:20 am, edited 1 time in total.
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Rick
Posts: 444
Joined: Sat Jan 04, 2003 8:34 pm
Location: Stone Mountain, Ga.

Re: Piston Ring Post Sizing

Post by Rick » Tue Sep 03, 2019 9:31 am

Jim
In two stroke engines the racers will go with exhaust port widths up to 60-70% of the bore.
I have a copy of Lima's standards, don't know if there is anything in it about this but I will look tonight.
Rick

“We make a living by what we get, but we make a life by what we give." Sir Winston Leonard Spencer Churchill (1874-1965)
"Peace is that brief glorious moment in history when everybody stands around reloading". Unknown
Murphy's Law: " If it can go wrong it will"
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Rick
Posts: 444
Joined: Sat Jan 04, 2003 8:34 pm
Location: Stone Mountain, Ga.

Re: Piston Ring Post Sizing

Post by Rick » Tue Sep 03, 2019 7:40 pm

Jim
Lima's standards do not have any info on port design.
Rick

“We make a living by what we get, but we make a life by what we give." Sir Winston Leonard Spencer Churchill (1874-1965)
"Peace is that brief glorious moment in history when everybody stands around reloading". Unknown
Murphy's Law: " If it can go wrong it will"
O-Tool's Corollary: "Murphy was entirely too optimistic"

Asteamhead
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Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: Piston Ring Port Sizing

Post by Asteamhead » Tue Sep 10, 2019 4:02 pm

Hello Jim,
Using 2 or 3 rows of drilled ports instead of milled rectangular ports works fine, too. There are no restrictions as long the diameter of the drills is below the width of the piston rings. Total cross section thus maybe up to 40 % of diameter x width x pi (liner port).
Just my two cents.
Asteamhead
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A valve liner made of bronze with drilled ports

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