Hello.

I have a 1982 Z28 Camaro that I've swapped a cracked 305 for a moderately built up 350, but I've been struggling to get the 350 tuned properly with the Q-jet. It starts up and idols at 750 RPM, but once it gets close to operating temp, the engine starts a slight knock, which caused me to shut it off, and immediately after, the engine started dieseling with the key out of the ignition, the carb shoots up some gasoline, and the engine is dead.
The timing is set at 12* advanced from TDC, the sparkplugs have all good spark, the wires are working as well. It has fresh gasoline, and I've tried experimenting with the electronic choke a bit, but I'm not too eager to continue making my rebuilt engine knock.

I've tried resetting the timing, and have hunted for a vacuum leak, but the vacuum gauge and levels are holding steady, even when I spray down the vacuum lines with break cleaner. My temperature levels are holding normally too, so it's not overheating. My current suspicion is that the carb is putting too much fuel into the engine, but I'm unsure.

Any and all help will be appreciated.

 

I'm not too familiar with built engines, but that sounds like an awful lot of timing.

 

Something is igniting the fuel after you turn the key off. Spark still lighting? Hot spot in the chamber? Too much compression? Low octane?