Any folks know 220 wiring ?

My air compressor isn't large enought to push a sand blaster..even though I was told it would. Drove 1.5 hours (one way) to pick up a bud's 220 compressor.

It has three prongs. My dryer outlet has a BIG plug so that was out and my generator has a 4 hole 220 plug.

I took off the plug and there are only three wires on the generator..I put a plug that fit my gen on. I tried wiring with one wire left off..I believe that it is a nutural but with no joy.

Went to a trailer supply store that sells generators that has been around for years and a couple of places like Home Depot looking for info or an adapter or a way to wire it..no luck. The Internet hasn't been much help either.

How can I wire the compressor's 3 wires into the 4 prong plug of my gen or has this whole trip been for nada..?

A pic..


Grassy