I just got this 1985 bronco and we've already replaced the starter and solenoid, but Everytime we try and start it it clicks and the solenoid starts to smoke.

The battery has been fully charged and this engine ran less than 5 months before but it's recently locked up. We can't get it to start but the most recent thing we've thought about doing is spraying some marvel mystery oil down in the spark plug holes and trying to loosen the Pistons.

Any advice here would help I'm hoping to get this truck running!

 

Check ALL the cables for dirty connections. If the cable looks questionable replace it.

 

Okay, I'll try that, but should that be a reason we can't even turn the engine with a cheater bar? We pull and pull and push but can't get it to turn up underneath. But I'll check the connections and try again, and come back with whatever the result is!!!

 

You should be able to rotate the crankshaft by using your hands or a wrench. If you pull the starter out, the ring gear teeth will be visible and using them to rotate the engine might help. But I would pull all of the spark plugs out to make sure that it is not hydro locked.
As to the solenoid smoke. At zero RPM, an electrical motor draws maximum amount of current. This is only limited by the energy source and the link with the most resistance. Resistance + current = heat, and this heat causes smoke. So until the cause of the engine not rotating is remedied, I would not use the starting system to attempt to rotate the engine.