I've seen stovebolt engines run with 50-60 lbs. of compression pressure, and as the rings free up it's not uncommon for a cylinder with very low compression to improve considerably. One chronic problem seems to be valves that suddenly seize up in the guides and bend pushrods after running for a short period of time, especially if there's any stale gasoline in the tank. It's a very good idea to use an outboard motor fuel tank or just a can of fresh gas with a siphon tube to supply the fuel pump for the initial startup.

Here's my favorite penetrating oil, made in Nashville Tennessee about 60 miles north of my farm. KROIL:

www.kanolabs.com

It's great for freeing up rust-frozen bolts and nuts, piston rings seized in their grooves, etc.
Jerry

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