SBC #5 Cylinder Wet?

Hi Guys, I am a newbie to the site and there seems to be a lot of good stuff here. I am building a 32 Ford tudor sedan and I have a new motor question that maybe someone can shed some light on for me. The motor is a Chevy 350 crate with Edelbrock RPM heads and their new dual quad air gap intake with 500 CFM Thunder series carbs. After running the cam in I noticed fluid (gas and oil mixture) running from the #5 exhaust port- actually dripping below the header. After removing both headers, all of the other exhaust valves appear normal- the #5 exhaust valve stem and port are wet- fuel/oil/black carbon... The spark plug does not appear to be fouled (strange). I have checked both floats in the primary carb (rear) thinking that the carb was dumping gas into the intake - the #5 cylinder runner is directly in line with the primary. The floats, needles and seats are OK. The cylinder compression tests at 140. I have cleaned the plug, checked the wire & distributor -all new MSD items. I have run the motor for short periods and continue to see this problem. What would cause just one cylinder to do this? Thanks for reading...

Thanks Denny, I hadn't thought about that. It might make sense because it appears to be above the chamber.