Setting the engine timing on all Briggs and Stratton engines occurs after the rebuilding process. There are two distinct types of gasoline-combustion small engines, vertical shaft and horizontal shaft. Vertical shaft engines are typically used to power lawn mowers and horizontal shaft engines operate larger rototillers and electrical generators. The timing is set in both of these types of engines by aligning the manufacturer's "timing marks" before sealing the engine cavity. Failure to properly align the timing marks causes the engine to operate erratically or not at all.
Wipe all surfaces of the camshaft and the crankshaft. You need to have all surfaces clean in order to find the timing marks made by the manufacturer at the time of engine assembly. The timing marks are one of two types; a round indentation or a short, 1/4-inch long, chisel mark.
Locate and identify the timing mark on the crankshaft counter weight or the camshaft gear. Different model engines will have either of these two locations for the marks regardless of the vertical or horizontal orientation. The crankshaft must be installed into the lower engine cavity first.
Slip the bearing end of the camshaft gear into the bearing hole. The camshaft gear will have the round indentation stamp on the end of the gear.
Rotate both the camshaft gear and the crankshaft simultaneously to align the two timing marks. This process may take several attempts to fit the gears together and properly align the timing marks.