Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

This is my Holt tractor engine. I had seen several of them over the years and heard different stories about how they had to be machined so I purchased the drawings and built mine from scratch. I purchased the flywheels and manifolds from Coles's when it was still in business. My crankcase is split at the bearing line making it much easier to machine.
gbritnell

Wow! I wish I had the skill and talent to build something like that! I really like the way
It sounds.

That's a great piece of work and the sound is amazing - had to watch the video a couple of times and will probably do so again. Well done!

Hi Swift Fox,
The engine was originally offered as a casting set with drawings from a company in the States named Coles. They sold the business to a fellow in Texas and he operated it until health or other reasons ended it.
I had seen the finished engine at several of the antique engine shows in the area and spoke with the builders, finding out the good and bad about the engine. From my conversations I determined that one of the biggest issues was the way the block was designed and had to be machined. At that point I decided to build my engine from bar stock. I purchased the drawing set from Coles and then redesigned the block to be made in two pieces to facilitate machining the main bearings and just general access to the inside. The block is made from 6061 aluminum as are most of the main components of the engine. The heads are cast iron as are the cylinder liners. When the engine build was started I opted to purchase the large rear flywheel and the intake and exhaust manifolds. I could have made each but buying them simplified the build significantly.
The carburetor drawing that came with the set didn't provide a very functional unit so I redesigned that following the lines of a model airplane carb but with the appearance of something that would fit the engine.
I made several versions of the carb until I got one that would operated fairly well through the entire throttle range. The ignition timing is with points and is set about 15 degrees BTDC. The video that I posted was taken by a friend and presents the running of the engine well. I have several videos or the engine running on my workbench. They can be found on Youtube on my channel: gbritnell

Thanks for explaining the build George, that does make a lot of sense. I assumed it had cast iron liners as well as the heads.  I will check out your YouTube channel!

Your steam engine builds are very nice too!

Excellent work! Over the years, I've found two of the Coles kits. Both times I've eventually chickened out and sold the kits to someone who could complete the engine.