4 Valve engines

I have a question regarding engine types for midget cars and I was wondering if someone can help me out. I happen to be looking at all the entries for the Chili bowl this year and it seems like most, if not all, the engines listed are standard 2 valve push rod motors. Is this correct? If not, which ones are the 4 valve type? I'm a new fan to the sport and I don't know exactly what the engine rules are for this class but it seems odd to me that a class that a class that runs mainly in-line 4 cylinder engines aren't using 4 valve OHC engines. Is anyone using a 4 valve motor?

Is there anyone who could help answer my questions?

thanks!

Scott