I am not an electrician, but I did receive it wired for 220 according to previous owner. I've checked the magnetic switches and it looks to me like it is wired properly when compared to diagrams I have showing 1 Ph, 220V. I also had it plugged into a 220v, 20amp circuit in my garage. I started it about 10 times, and ran a 6ft piece of 3/4" plywood through it before it stopped.
I thought it may have been wired for 120V because the start capacitor that blew was a 120V rated capacitor, not a 240V rated capacitor. I'm really trying to find out what start capacitor is supposed to be in this engine as I think the one I'm replacing may not be correct....
I'm not an expert with motors, but have worked a lot with them over the last 40 years.
Let's look at what exactly the capacitor is and what it is doing. At the dam, a rotor spins past magnets which wired up in three sets- A, B, and C. Each set is called a Phase and connected to a wire, so you have three wires coming from the dam, A phase, B phase, and C phase. When the wires get to your shop, you connect each wire to one of the three in your 3 Phase Unisaw motor and you are good to go ( I'm simplifying this just a tiny little bit). The direction the motor will spin is easy, it will spin A B C just like back at the dam. If you want it to spin the other way just change it to A C B. So simple.
Problem is, you've got Single Phase, which is just two of those wires. When you connect the motor to A and B, it has no way to know which way to go, so it just sits there and vibrates, while getting hot.
In a Capacitor equipped motor the capacitor is wired onto one of the phases, in your case both are 120v phases. The capacitor acts like a bucket for the electrons. The effect of that is to make the power from the capacitor phase 'late' getting to the motor, because it had to fill up with electrons and that took time, allowing the motor shaft to rotate more into the opposite phase's pole (magnet). Having filled up (charged) the capacitor with electrons, now the capacitor discharges but the motor shaft has rotated enough that this discharge is now 'pushing' the shaft in the direction you want.
This entire process is called 'lagging' and most likely takes place on only one of the two 120 volt phases. So a 120 volt capacitor is probably fine.