Compression Test

[Lionized]

If it was rebuild and barely run, I would think more likely of corrosion or carbon build up that causes a valve to slightly leak.
The head gasket will be something if the rebuild was not done right and the deck and head were not resurfaced causing a leak.
To me if you rebuild an engine you will never skip that process.

I would put some more miles on it, high way driving with some power on it to burn it clean and after test again.
Maybe throw a known brand of fuel additive for cleaning the internals in the tank. (not sure if that is any good to these engines but on modern engines it does make a difference with a "lazy" engine full of carbon build up.)

I'm going through a tank of CRC 1 tank right now. Low compression in two cylinders.
Before I used the additive I ran about a quarter cup of water through the primaries after letting it warm up. Slowly drizzle it down each bore a bit at a time keeping the rpm up. Should take care of any carbon build up.

 

[69 R/T]

Hey guys, thanks for all that great insight. I'll take the advice and drive her more. I have all the engine rebuild receipts and it was done like I said maybe 2000-2001, and this motor is tight. The oil pressure is high and runs like a champ, so you guys are probably right... it's been sitting too much. It never leaked oil and now it's leaking oil because the gaskets are drying up I think.

 

[biomedtechguy]

I guess I opened up a can of whoop-*** on myself

So..you're sticking it to yourself? Lol.