Hello, welcome to the world of building things, or drawing them.

Perhaps you could put in a link to a picture of whatever a 25c is so we can understand a bit more. I found several different thins on google so not sure which one you are talking about.

Hi John, welcome to the forum.

Before retiring from work, I used toi be a CAD jockey and model everything that I intend to make prior to machining. Much easier and cheaper to fix mistakes on a computer than in the workshop. Whether you are making your own set of drawings from scratch or modifying a set of purchased drawings, my advise is to do it in CAD first.

Most of the drawings that I have seen for model engines seem to have been drawn by amateurs and contain errors but they are in-expensive. (the cost of professionally drafted drawings would cost thousands of $, not a hundred). They may also use older, imperial size materials which are hard to find..

Good luck building your project and I look forward to seeing your progress.

Paul

A very ambitious first project John – but it sounds like you have a good background for the work.

Having had a look through Jim Nolan's site – I think you really need to contact him and ask for his advice and see if you can co-operate in any way. He's had castings made, so will have patterns and contacts etc – and of course, he must have drawings (possibly CAD) he's working to.

I think John B has possibly saved you a great deal of time and effort in pointing you at Jim's work…

Regards,

IanT