Base setting for a 2150 is 1.50 turns out...
If it starts and instantly dies, it could be the mixture screw settings. But since it just cranks and cranks, I'd suggest you look elsewhere... Whether they are all the way in or all but removed, it should fire off. (The setting has virtually nothing to do with cranking or running when off idle.)
The engine must be warm when setting the screws, so the choke should have been fully open...
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I agree it is probably flooded now...Pull a few of the easy to get to plugs and see what they look like. If they look OK, look for a vacuum leak. (Possibly cross-wired?).