I am working on removing the block drain plug.
The engine is a 66, I think, and the plug probably has never been out.
I removed the paint from the threads and soaked it in penetrating oil for a week. The engine is in the car.
I got the right front wheel off.

I am using a manual impact wrench, a few extensions, and a sledge hammer.

Is it possible to crack the block this way?
The impact socket is right up against the block.

UPDATE:
I put a breaker bar on it and it didn't move.
Then I hit the breaker bar while putting 50-60 foot-pounds of pressure on it, and it came loose!

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63 Signet / 10 inch front drums / weber 2bbl / HEI / 2.76 rear end