Welcome, your post reminded me of an old chap who taught me woodwork, his favorite saying was "I built it completely off the top of my head and I have plenty of material left! ". I am sure you will get plenty of sensible answers and once you have done a few posts you will have access to the downloads section of the forum where you will find plans for plenty of engines. I you post some idea of what you want to use your next engine for I am sure there will soon be lots of suggestions as to which plan will be most suitable. Cheers, Ian.