"I think the gearing is about right, but I still need to figure out my maximum RPM and see what my top speed will be. I have 17 tooth sprockets on the crank, and 31 tooth (or 30) on the jack shaft. I'm thinking that at 150psi I could go up to 20 teeth up front, it seems to have the torque no problem." Jim, That is a 1.7:1 ratio. I'm running 2.5:1 16 and 40 tooth with 27" OD wheels. I can run 40 mph @ 200 - 250 psi, but it really needs second gear at that point as the engine doesn't sound like a piston engine anymore, sorta goes in to a high whine/turbine sound. That is the ratio the Locomobiles came from the factory with so that is where I will leave it. And too riding atop it at 40 mph with tiller steering and zero safety equipment is scary as hell, wouldn't want to go any faster. (attached a pic of it) Locomobile did build a racer that was 1:1 ratio and they could hit speeds of 70 mph, not much out the hole more than likely. Diverter valve engines don't breath very well - the intake passage is also the exhaust port, causing thermal issues. The reasons for the advantages with Uniflow designs with separate intake and exhaust routing. I would leave your gearing just as it is and try it. I think when you start making enough steam, you should get 50-70 mph without too much effort. Good job keeping the weight down. Trying to figure out max RPM and speed on paper with any engine/vehicle is about impossible. Steam although simple in concept is actually quite complex. And especially when speed and load are factored in. I'll resort to our favorite adage amongst my steam buddies when we question what will work : "Try it". To make it go fast gotta have three things: Enough boiler heat surface, large enough engine, and alotta heat. ""The next issue to work out is my valve timing. I think that the eccentrics on the crank are optimised for reverese rotation, so I might try and use a later cutoff for a little more power in forward rotation." I noticed in one of your videos, the right side cylinder looks too far advanced. Locking slightly before TDC. There are numerous ways to set the timing and the majority of the modern steam engines I've encountered are typically out of time Most are simply set by eye - rotating the engine around and setting admission to open at TDC with the valve cover off. Some say before TDC, some say after - read on. Another way is putting a hose on the steam chest and blow into it and put the piston on TDC, adjust eccentric where it just opens at that point. I concocted and used that method and it works well. The best way is put the engine on a prony brake (easy to make) and adjust the timing to where it has the most power at a controlled inlet pressure. And use steam for this method as air and steam expand at different rates. The two latter methods have to be done one cylinder at a time not manifolded together. P.S. With those windows on the boiler casing and the right fire, it's going to look incredible at night. Probably get the fire department called on ya, but it will look incredible.