Hi there,

As Jens said, you don't really need any kind of 'fancy' cast iron to make the parts. Any cast iron (without flaws) should give you good running parts and good longevity. If you do get a specific type of cast iron, then meehanite cast iron is probably recommended, but not a necessity.

Again for the steel, almost anything will work reasonably well, so you may as well get something that's easier to machine. If you are going to be using a cast iron piston, then steel is probably better for the liner than cast iron. It will probably last longer (avoiding iron running on iron) and is easier to a certain extent to machine, as you won't have to deal with thin-walled iron cylinders, which are very brittle and delicate.

www.modelenginenews.org is a great site with LOTS of information. It's definitely recommended reading and is especially helpful for the beginner.

Regards
Warren