Here is 3 pictures of an engine made except for igniter points of wood or tree products. For springs he used rubber bands. It ran when first built but has since warped a bit. Built by Paul Gorrel the Crosby man at Mount Pleasant Old Threshers Show .
When I stuck my finger in the exhaust to see it there was residue, his son exclaimed he was going to put a mouse trap in there for all of us non believers.
There was a guy at jacktown, who had a wooden internal combustion engine. Ddnt run fast, and was hit & miss. he only ran it a few minutes at a time. main problem, he said, was the exhaust valves didnt last long.