Small Engines (Lawn Mowers, etc.): tecumseh 155020b (8 horse) compression, compression engine, ariens

Question
Engine won't fire. Cleaned the carb and set the screws to 1 and a quarter turns. This is on an old Ariens snowthrower. Ran comp. test and it shows 55 lbs(don't know if it has decomp valve or not)It has good spark and good fuel-think it's time for rings?

Answer
55 isnt too  baddddd  .it should still run. i dont believe that is keeping it.  clean valves by  seat  of any carbon using a wire brush. see if you can tell if there is any bad area,s on valve  showing signs that it is not  seating.
if its got fuel to cylinder it should fire up..  giving it a small shot of starting aid >  does that do anything??