Engine cranks, then slams?

I've been working on this old honda cvcc as a project car for a while, and I just got her to turnover the other day. The engine stalled last time, I wanted to idle it up to temp, but she stalled out and died first, I think its because the car ran out of gas. Now whenever I crank the engine, I can hear and see gas trickle into the carb, but she never starts, usually I have to reconnect the battery, and it sparks, and almost sounds like it wants to start, then there's a loud slam and then it just sounds like its free spinning. I'm predicting the starter isn't getting enough power or ground?

Try spraying starting fluid into the carb. The old gasoline might not be workable anymore…

The free spinning sound could be an indication of lack of compression. Check the cylinders compression. If you don't have a compression gauge just remove the plugs, put a finger over the plug hole turn the engine over. You should feel the compression pressure. If you have pressure then, with the plug wires attached, ground the plug and see if there's a spark when you turn the engine over. If you have spark and compression then it's either fuel or timing.

It sounds like that when the cam belt breaks and the pistons slam into the valves. Then the engine cranks faster than normal. Big trouble. That's why you replace the cam belt before it breaks. Now you need the top end rebuilt. The first time you saw the timing was off, that was your big clue the timing belt was slipping.