OldIHC

We have a 1955 Metro Van with what I believe is a SD 220. It has been
sitting for years and not been started. I want to do everything I can not
to damage the motor in any way when I go to start it up after having
set so long. I have read on other forums about pre-oiling the motor before
trying to start. How is this done? Are there other procedures? Any advice would
be appreciated. Thanks

Certainly ATF or light motor oil down the cylinders can't hurt.
I would try to pressurze oil system if possible.
An electric drill turning the oil pump with fresh oil is a great thing to do.
I've used a plews oiler ( just a trigger-style oil can) with fresh oil injected into the oil pressure sender hole too.
Don't forget some zinc oil additive for the camshaft. It was removed from oil in later years because it was slowly killing cat converters.

I forgot to say that one of the synthetic motor oil mixes might be the ticket. Synthetic oil is very, very slippery.
Gets into places regular oil won't.
Full synthetic would no doubt cause (more) oil leaks on that engine.

I like to pull the plugs and squirt a light oil in the cylinders. I use mystery oil. Let it sit. Then I come back and get a socket on the crank pulley. With the plugs still out, carefully start to turn the crank. Go slow. Rock it back and forth a little. Eventually get it so you can turn the engine crank all the way around. I like to pull the valve cover and make sure what goes down comes back up. If all seems free, spin it with the starter, again with the plugs out. Don't be afraid to keep adding the light oil. She'll burn it off once she's running.

Before you turn the engine over, remove the valve cover and make sure the valves are not stuck. Otherwise you may immediately have some bent pushrods.

Dean

Over the years I have started several engines that have sat for years. I normally confirm that it can be turned over by hand first by pulling the plugs and putting a wrench on the crank snout. If it turns over freely by hand, I change the oil and filter and crank it a few times with the electric starter. If all is going well at that point I reinsert the plugs and give it a try. Most of the engines I have restarted had some electrical issue that frustrated the prior owner so much they give up. Solve the problem and they almost always start. Sometimes the engines are really tired, but should run. Good luck.