B&S 20M114 - 0138E1 Sprays gas out of OHV Cover

Hello everyone.
 
I picked up a Snow blower with a B&S 20M114 - 138E1 engine, it fires right up and runs smooth but after running for a minute or two it will suddenly bog and start spraying a oily gas mixture out of the OHV vent. My initial thought was possibly a bad cam not allowing the exhaust value to open enough to vent, causing some pressure to exit the intake. But when I pulled the OHV cover, both rockers looked to be in proper adjustment and the valve movement seemed normal.
 
With the ignition off, I hit the starter and saw a lot of oily fuel spraying out of this passage in the head:
 

 
I'm not entirely sure where that passage goes, or why oily fuel would be pressurized to spray out of it. The previous owner tried a new carb to fix the "spraying fuel" issue, but that wasnt the root issue. He thought it was a burnt valve... but I dont understand how that would affect it spraying fuel.
 
It did not do this on first startup after sitting for a few weeks. But after running 1-2 minutes the motor suddenly started to bog and the fuel started spraying out of that passage, into the OHV area, then out the OHV Vent line.
 
Its very cold outside right now so I dont want to tear into it further than pulling the valve cover off. Does that passage connect to the carb or intake? Or is it a passage into the crank case? Maybe the crankcase is full of gas that gets pressured up into the valve area after it warms up?
 
I've rebuilt alot of engines for fun, this issue is rather odd to me.
 
Any thoughts from those more experienced with this model?
 
 
Motor serial and model:
 

 
Misc serial on recoil starter, possibly the snowblower serial itself?

 
And yet another serial, this one on side of fuel tank.
 

 
 
 
-DallanC
 

Holy Moley... the guy I got this off of said he was a fairly competent mechanic. I assumed all of the "easy" causes were already looked into. Checking the oil level... apparently he never did that.
 
Ok so I knew this was the root issue when I started to loosen the dipstick, and saw gas leaking up around the threads... it was full of fuel... WAY over the top of the oil fill. It started making a helluva mess before I stopped it back up with the dipstick. I'll drain it all out later and get it refilled with some new quality oil.
 
So what I think happened is his float got stuck, and drained a couple tanks of gasoline into the crank case. He said he replaced the carb, I'm going to doubt that for the moment. He got rid of it due to the gas spraying out of the OHV vent... which of course we now know is because the entire bottom end is full of gas. I'll pull the carb and replace the float needle and seat. For good measure, I'll probably add in a fuel shut off on the line from the tank to the carb.
 
Thanks, I should have started with the oil level... but its well below freezing outside and with the information the previous owner gave me, really suspected valves bad exhaust lobe on the cam. This might just be a cheap fix.
 
Thank you for the advice!
 
-DallanC

Now thats a great idea, thank you.
 
-DallanC