1978 80hp mercury outboard wont turnover

Hello. Just purchased a boat that has a 1978 80 hp mercury outboard. I hooked up my battery and lights come on as well as the fish finder and bilge pump. When I turn the key on to start the motor -the starter clicks once then nothing. I want to try and manually turn the motor over just to make sure it is not frozen up. I tried to turn the flywheel by hand and could not get it to budge. I do have the pull rope but wanted to see if there is a step I need to do before just pulling on the flywheel. Any tips would be greatly appreciated. Thanks

Either the power head is frozen up or the lower unit. You could drop the lower unit a few inches (holding it up with bungee cord) and see which it is.

Jeff

Thanks Jeff, I will have to try that--Think I will pull the starter and see if that is seized also.

Pull the plugs first,easier to turn over by hand,then,if that doesn't work,Jeff's right

Thanks, I will pull the plugs and see what happens with fingers crossed.

Update, I dropped the lower unit and power head still wouldn't turn. pulled the plugs and with some help with a socket on the flywheel nut- i freed up the power head unit. I hooked up the lower unit and can still turn the flywheel by hand. Before connecting a battery and turning the key--anything else I need to do first like any lubrication I could use for the cylinders that i might squirt in the spark plugs to help?
Thanks

Check compression, if that's good then water pump, gear oil, new spark plugs, you might need to do the carbs if they are gummed up. Make sure to use quality oil and fresh gas. It's an old motor and might take a bit of tlc.

I would spray WD-40 into the plugholes.It'll affect the compression numbers a little but will oil up the cyls and soften any rust lines from her sitting.Spray some in around the top and bottom bearings as well.After that,as Fivestar says.You'll be looking for 110+psi