Model Engine Maker

Help! => Specific Engine Help => Topic started by: paolo1959 on June 08, 2021, 04:15:02 PM

Title: hit e mis engine
Post by: paolo1959 on June 08, 2021, 04:15:02 PM
Hello from Paolo from Italy.
I have the problem of finding the cylinder liners and segments for my internal combustion engines.
Where do you buy them ???
I usually use the red o rings but they do not last long (a few hours of engine operation)
Thank you in advance for your help.
Title: Re: hit e mis engine
Post by: Jo on June 08, 2021, 04:54:15 PM
Caio Paolo,

If you are making your own model then we normally machine our cylinder liners. They can be made of cast Iron or in Aero engine models steel (EN8) is often used.

The term "segments" has not translated correctly into English: You have mentioned the red silicon O rings so do you mean the rings for the piston? We also turn those up ourselves out of cast Iron. In the UK some of the Model Engineering suppliers will supply them but in limited sizes. You should also be able to buy them in Italy. Think of small IC engines, like Lawnmower engines and see if you can find one with the right bore size.

If the Silicon o rings are not lasting very long it could be that the liner surface is still a little rough. Cast Iron rings "bed in", i.e. wear a little against the cylinder liner this makes the bore of the liner smoother. What this means is you need a better finish on the bore of your cylinder if you are going to use O rings.

Title: Re: hit e mis engine
Post by: Jasonb on June 08, 2021, 05:14:56 PM
If you are using red O Rings then they are not the best material for hit & miss engines, OK for steam. You need to look for Viton rings, these work well in a honed bore.
Title: Re: hit e mis engine
Post by: paolo1959 on June 08, 2021, 10:40:41 PM
Thanks so much for the advice.
i am looking for a shop that sells piston rings.
the problem of the cylinder liners (but it can be my fussiness)
and that with a common lathe it is not possible to have an appropriate finish.
and certainly the functioning of the engine even with only an o ring seems to improve the finish but if you measure it you can see that it is not necessarily perfectly round and perfectly cylindrical.