I recently inherited a 1987 Monte Carlo SS and I'm trying to just get it to turn over so I know I'm not just dumping money into a lost cause. I replaced the starter, and the engine turns a little but stops. All the spark plugs work and when I took them out the engine spun freely (I put each spark plug cable I their original spots, so that is not an issue). So the engine is not siezed but something is stopping it from turning freely. I am aware that all the fluids in the car need to be replaced but I just want to verify it turns over first. The valve covers are moving and I oiled them as well as the cylinders with some penetrating fluid. Does anyone have any suggestions or ideas? I'm pretty new to this so I'm not entirely sure what I'm doing so any advice would be appreciated. The car needs a lot of work but I would love to see it drive again.

 

I have heard of some people manually operating the oil pump to get oil re-distributed through the engine. Off hand, I am not sure the best way to do that.
You are trying to start it and believe something is preventing the engine from making full revolutions. You could try using a half inch socket a long ratchet/breaker bar and manually turn the crank. You might get some resistance when parts of the engine are under compression, but in general, it should rotate pretty easy and freely. If not, there might be an internal problem.
But, assuming it does rotate freely, keep in mind, an engine needs three things to run: Air, fuel and spark.

So you will want to validate the air path is not restricted (like an old clogged filter or a mouse nesting in an air duct). For spark, you can get an inline light made for testing spark (easiest method to explain). Harbor Freight sells those. You can have one guy watch the light and another turn the key. If there is no spark, then hunt that issue.
Fuel, on an 1987, I am not sure if that is a mechanical fuel pump (bolted to the engine) or one in the tank. My guess, in the tank. If it is in the tank, listen if the pump hums when putting the key in the on position. There are other tests to check fuel pressure.

Those are a few ideas. As well as make sure it is a good battery. Just because it has 12v, does not mean it's putting out the amps to get the job done to start the car.