I'd like to build a freelance horizontal engine that I can fabricate from oddments in my collection of offcuts. This would by about 1" bore x 1.5" stroke - can anyone suggest what the ieal valve travel and port spacing would be for an engine of this size - I can't find any suitable drawings to use as a basis.
There are a number of engines around with this sort of size bore. Immediately to hand I have the Diagonal Paddle Engine drawings (3/4" bore * 1 1/2" stroke) , that has 1/8" inlets, 1/8" lands and then 1/4" exhaust ports, all 1/2" wide. Valve "cup" is 1/2" * 5/8". I also have the Brunel Tandem Compound which both the HP Cylinder: 1" bore * 2 1/8" stroke and LP cylinder 1 5/8" bore * 2 1/8" stroke , which has smaller identical ports of 3/32" inlets, 3/32" lands, 3/16" exhaust, at 3/8" wide.
Clearly neither designer took to calculating the fine details of efficiency but they both run well.
Thanks for that, I'll give it a go and let you know how I get on - don't hold you're breath though, I've got my Sweet Pea to complete and steam test, then build a tender for it! Fortunately I've got another four or five weeks of sick leave following a heart attack, so hope to finish these jobs off in that unexpected bonus time!
In 1956, Edgar Westbury designed Perseus and Theseus, similar engines but one built using castings (which are available from the trade) the other, Theseus, using stock materials. Both were fully detailed in ME, so would be a suitable basis for your engine.
I believe they are 3/4" bore x 1" stroke.
If you dont have those issues and would like them, let me know and I will scan the relevant pages and email them to you.
I took Alan's reference and brain-skipped it to 1957. In the 18th July edition and alternate copies thereafter for ten articles there's a series on a "60cc Horizontal Gas Engine" by Edgar T.W full of useful info.
I also found some good stuff on making pistons including clearances, piston rings, etc all by Mr Geometer as I searched through the year.
I'm going to have to hit the club library for 1956 now.