While you wait for answers, we may have found some information which could help you.
Click here for Timing Briggs Stratton Enginemy briggs and stratton 3.5hp starts up then cuts out straight away?
westwood t1200?
Adding oil to mower ?
How can I fix Mountfield Laser Omega 46 Lawnmower?
Petrol or diesel?
lawn mower briggs and stratton classic 35?