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The thread? Re tap it.
Or the keyway? Uh-oh.
Go invest a couple $$ in the proper tools to get the job done. Will be so much easier and better than trying to roll around on the floor.
If I were you I would try to drill it out or do whatever it took before taking the crank shaft out, its worth a shot if your careful.
Atleast buy a stand.
Find a mate that has a engine crane.
How have you tryed to remove the cone part?
The bolt is to hold the balancer there. If its damaged the thread just re tap the thread. It'll be fine.
sounds like you have a boat anchor, get a replacement engine and drop that in..... quicker and easier than trying to replace the crank
Tried old fashioned heat and lots of it with a lh threaded bolt? (only problem here is damaging the seal and/or timing cover which houses the oil pump.....