I was given a 16hp Vanguard model 303777 that was supposed to have blown up. After a total tear-down, no broken pieces were found, the bores had no sctatches or ring groove. The exhaust and muffler were saturated with oil. I replaced the necessary gaskets, head and others. When the engine was finally started, it ran OK for a minute or so, but began to rev up and smoke and pump oil out through the carb breather pan. It dieseled so bad the key wouldn't stop it, so I had to jerk the plug wires to shut it down. I drained the oil, and it had a couple of qts. Gas mixed in.

After 2nd tear-down, I had the cylinders honed and inspected by a professional, and he said all was perfect. I installed new std size rings, but used the same head gaskets to rebuild. I also lapped the valves. After start, it run some better, but then same problem, but no oil in the exhaust. Just pumps oil out through the inside breather pan. I unplugged the fuel line immeadiatly, drained the oil, and it was half fuel. I'm looking at it once more like CSI. The intake manifold is oily. Does anyone know what might be the problem?
Thanks, lm