Adjusting values- not going well!

[YnotRoman]

I have a Craftsman 21.0 / 540cc Briggs Stratton motor. Model # 917288515. Engine model # 331877 2371 G5. Replaced battery/ starter solenoid/ ignition switch. I get a 1/4 turn from the motor and won’t crank (googled the issue and seen many videos to adjust the valves). I tried many of them with the same results. The last one I tired- TDC piston went about 1/4” further and adjusted intake valve to .004 and the exhaust valve to .006. Same result- so I removed the spark plug (and did something I know I should not do) sprayed a squirt of stater fluid - turned the key, motor turned over with a pop or 2 out of the carb and it started and the mower ran - cut my lawn - pulled into the garage and turned off the mower and some little back fire or pop from the carb. With the motor still warm - mower started. I tried the next day - same results- 1/4 turn of the motor and Nothing! Need Help! I’m sure I don’t have something adjusted correctly with the valves but I’m at my wits End!
Any ideas would be grateful!

 

[hlw49]

Broken compression release. Try turning it backwards until it comes up on compression and try starting it.

 

[YnotRoman]

Broken compression release. Try turning it backwards until it comes up on compression and try starting it.

Thanks - I shall give it a try and will reply later.

 

[bertsmobile1]

Or a worn cam
I had a customers mower that would not start early in the morning.
By the time I got there it was lunch & the mower had been sitting in the sunlight for several hours
It would fire right up without a problem
Next weekend, the same thing
So I did a valve lash adjustment
Next week, same thing again so I tightened the lash a bit more
Same thing next week
Eventually he just resigned himself that it would not start first up on a cold morning having spent all night is a cold steel shed
At the end of the season I stripped the engine to find the exhaust cam just about full round