Ron, I had a very similar situation with my car two summers ago. It would start and run fine most of the time. Every once in a while it would not start and I would have fuel pouring out the vents. I have a Mallory 140 and at that time a holley regulator. It ended up being debri in the regulator that every now and then would allow the regulator to stick open and cause the full pressure of the fuel pump to push past the needles of the carb. This may be the same situation or maybe not, but it does sound very similar to mine.