Author Topic: Questions on the Elmer 33 Engine  (Read 8100 times)

Offline Stuart

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Re: Questions on the Elmer 33 Engine
« Reply #30 on: March 25, 2014, 09:34:27 AM »
Running on steam

well two choices

one bronze with a different grade bronze piston and soft packing  ( i mean say cast for one and drawn for the other bit )    this combo is good if you do not run often no rust
two Cast Iron cylinder and cast iron piston with CI rings or soft packing  will rust up if not used often

note in both cases you will need a lubricator in the steam line displacement type will be ok ( note this will not work when run on air) a mechanical one will do both air and steam

I have seen loco's that have bronze cylinders and cast ali piston ( but the ali was not degassed and was left full of bass inclusions to hold the oil , soft packing in this case )

note if you are using super heated steam at 100 psi then only CI is good enough the temp would be a bit high for a bronze set up , but it would work but not as good as CI

IMHO  use CI and CI rings and do the job properly

Have fun

Stuart
My aim is for a accurate part with a good finish

Offline Heffalump

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Re: Questions on the Elmer 33 Engine
« Reply #31 on: March 25, 2014, 11:41:52 AM »
Thanks Stuart. I think I'm probably looking around 30-40 PSI max for simple steam.

Why is Ali no good?

Offline Stuart

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Re: Questions on the Elmer 33 Engine
« Reply #32 on: March 25, 2014, 12:47:05 PM »
Unless you can dry it out it will corrida with the white deposit you will have seen
Also it will expand with the heat and produce a poor fit for the piston

BTW when I say soft packing it's graphited yarn , I do not like silicon o rings as piston rings ,because unless you can hone the cylinder to a mirror finish and produce the grove to the o ring data tables for the use that you are doing it will not work long term

Soft packing has been used for years , as have CI rings ,but you will need to heat react them to get the spring correct


But I am sure others will chip in and give you a different opinion but my advice is based on my experience over 40 years

Stuart
My aim is for a accurate part with a good finish