about 33 mph
That is the main jet needle valve.
The correct spark plug for a 5 hp. Tecumsen 4-cycle motor is Champion J-8 (RJ17LM). The plug gap is 0.030 in. (0.76 mm)
Brigg's and stratton 5.5 hp on the craftsman push mower your gap tool set the gap at .025-030 for briggs 5 hp
.030
.020in
If that is a 5 horsepower Tecumseh engine - ( .030 inch )
.035
45 to 60 thousands,
5 to 14 thousandths
An Autolite 258 is the recommended spark plug for a 6. 5 horsepower Tecumseh engine. A Champion RJ19LM also is recommended by the manufacturer.
twenty eight ounces