BUYING an old engine HELP!!!!!

Is it running ? If so, that would be nice because you could hear it run and check the oil pressure if you take a gauge and adapter. You could also do a compression check ? But, if you are gonna rebuild anyway, may not be worth the trouble. If I was looking for a builder, I would just want to hear what I was buying and see that it was complete. See if he will "make it good" if you find any surprises internally. Good luck !

Well, if it's out already, hearing it run is out of the question. How soon are you gonna rebuild it ? Any chance he would let you take it to your shop and let them tear it down and inspect ? I would hate for you to get a block that has been bored a couple of times already.

You can get a good idea of the condition of an engine by looking at the spark plugs, the end should be brown.If they are black and oily that is a bad sign and if you pull a spark plug and find antifreeze or water that is a very bad sign.Rotate the crank with a socket on the front and make sure it turns over ok and is not seized.Since they are selling it as needing a rebuild you have to assume that at best it is tired, at worst it needs major mechanical parts.The cost of a "rebuild" can vary greatly.A true rebuild would involve boring out the cylinders, grinding the crank ,new valve guides and replacing just about every moving part in the motor with new ones which can easily cost over $2000 with standard parts and more if you are replacing them with hi-performance stuff.In that case you might be better off just looking into a crate motor, especially if you would have to pay someone else to assemble it.