Mower spins but won’t turn over

The engine should not turn over if it is bolted down. <LOL> But I know what you mean as it will not start and run.
 
Then the question is did the valve guide move? Another question about the backfiring as I know most says backing even when it is out the exhaust. Is out the exhaust or intake? Also I had one 310000 series that was what I call sneezing out the intake which was an intake air leak but was when the engine was running.
 
Depending on the engine model, type, and date code as I assume it is a single cylinder Briggs. It can be a sheared flywheel key on top of the valve problem. Especially if  it is older 280000, 310000, or 330000 series.
 
As to if it a camshaft problem depends if the valve lift is correct or not. I have yet to see a cam lobe to rotate on the camshaft.

Was it what I posted that need clarification of?

Trust me I understand the lingo can be confusing. What I meant is the flywheel is spinning but engine won’t crank over/start. The valve guide looked to be seated correctly and didn’t move. I took off the air filter and sprayed a little stater fluid and then it would “backfire” out air intake. I made sure the valves were set at the right specs and the valves are opening and closing.

I checked initially at the flywheel key and it looked ok but I’m going to take another look to make sure I didn’t overlook something. Model 917.289210 engine # 331877. Appreciate it!

This is why I asked for the engine's date code so you would be using the correct key and torque specs. First if it has a date code before 120701xxxxxxx the key needs to changed to a steel key and the flywheel torqued to 110 ft-lbs. After 120630xxxxxxx the key will be the longer 1" key and the flywheel torqued at 110 ft-lbs. Plus during at time in 2016 some flywheels were under torqued from the factory [160501ZDxxxxx THROUGH 160922ZDxxxxx].

Note also that the flywheel and crankshaft key ways were change at the same the new longer key was issued.

I checked the part number for the flywheel key and I am using the correct steel key #222698s

Definitely appreciate the information, I’ll grab the steel version. I’m sort of at a loss to figure why it won’t turn over then. Pretty much checked everything else, besides possibly being a carburetor problem? I’ll continue to see if I can find out the culprit.

If the flywheel is spining it is cranking over, just not starting. Recheck the push rod, it may be bent again indicatinng a loose valve guide. Did you properly torque the flywheel nut? If not it may be sheared again.

soulsnipes40
So everything is still the same. Flywheel is spinning but not cranking over. Also I have to jump the battery because if not battery goes under 12 volts after a few spins. Also I noticed a lot of oil coming out of the exhaust valve where it connects to muffler

Something definitely not right as there shouldn't be a lot oil coming out the exhaust at any time. Is the crankcase overfilled? If so then it is likely the carburetor is leaking and has flooded the cylinder and polluted the oil with fuel.
 
A flooded engine will not start.

AVB thanks so much for all your help. I emptied the crank case and installed a shut off valve. I cranked it over and after a few seconds it finally started. There was white smoke coming from the exhaust and the muffler was getting very very hot. Reasons for this?