Resizing cylinder bore

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Kevin_S
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Resizing cylinder bore

Post by Kevin_S » Thu Mar 30, 2017 3:39 pm

I have an older RRSC American that needs the cylinders resleeved. The plans I have call out for a 1.75" bore. The newer ones call out for a 1.5" bore. What would be the pros and cons of boreing the new sleeves down to the smaller size. Yes I know I will use less steam. I also plan on making new pistons for it regardless of what size I go with.
Thanks in advance for any input.
Kevin S

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Dick_Morris
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Re: Resizing cylinder bore

Post by Dick_Morris » Thu Mar 30, 2017 4:19 pm

Mine are 1.5" and I never suffered from a lack of power for the amount of traction I had. I operated at 125psi. Less steam would also mean less water usage and more range.

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LivingLegend
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Re: Resizing cylinder bore

Post by LivingLegend » Thu Mar 30, 2017 7:44 pm

Unless it's been redesigned at some point over the years, the piston bore of a RRSC CP173 is 1.500 diameter. That's the bore as designed and marketed by the original (Chet Peterson era) RRSC. The RRSC cylinder casting was bored to 1.750, as I recall, to receive a liner having a wall thickness of .125.

I would keep it at 1.500 piston bore.

For comparison, the Disney 173 (and other original Disney 173's built using it's drawings and castings) had a piston bore of 2.125 diameter and no liner. The Little Engines 2-6-0 had a piston liner bore of 1.625 and the cylinder casting bored to 1.875 to receive a .125 wall liner.

LL

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Kevin S
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Re: Resizing cylinder bore

Post by Kevin S » Thu Mar 30, 2017 8:08 pm

Living Legend, mine was one of the first ten produced by RRSC. There has been a few changes from them over the years. The original pilot wheels where 1/4" bigger. I actually like the bigger wheels.
My plans do call out for the 1.75" bore.
-Kevin S

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LivingLegend
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Re: Resizing cylinder bore

Post by LivingLegend » Thu Mar 30, 2017 9:30 pm

I will say this....

Dick Bagley's Disney 173, having the 2.125 bore could pull like like crazy.

LL
Do it right.... Or don't do it at all
I have no life. Therefore, I have a hobby
It's not that I'm apathetic, I just flat don't care
An Intellectual is nothing more than an Over-Educated IDIOT
Blogs: Where people with nothing to say..... Say it

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Dick_Morris
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Re: Resizing cylinder bore

Post by Dick_Morris » Thu Mar 30, 2017 10:18 pm

Build start number for my CP-173 was in the early 30s. I think I started it in 1973. The earliest drawing I have showing the 1-1/2" piston OD is November, 1971. The liner is 1/4" thick. None of my drawings show a change from a larger bore but I have always wondered if the bore had been larger because of the thick liner.

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