Based on everything I have read from Brigs and Stratton, and talking with some small engine repair guys I know, the 342cc engine puts out about 11-12hp, and the 420cc engine is about 15hp. Hope this helps.
If you have a different brand spark plug, Champion will have a cross reference. You just need the number from the plug. If you do not have that, you will need the model number from the engine. Briggs and Stratton built a LOT of engines with customizations that may use several different spark plugs. 342 cc is simply not enough information.
13.68 horsepower
just bought a craftsman snow blower yesterday. 3 manufacturers, MTD, Briggs and Stratton and Husqvarna. was told MTD 357cc was chinese can`t even find a torque # for it, Briggs and Stratton 305cc and 342cc made in USA, they had no Husqvarna so i don`t know about motors. was told Briggs and Stratton were not only making the motors but the whole machine, on the Pro series i bought which has the Briggs motor, if you look on the chassis it says built in the USA. This information i was told at a Sears store. hope its correct.
Displacement does not translate directly to a horsepower because of other factors, mainly engine design. One could predict a range that would be from 13 to 17 HP
208 c.c. is 12.7 c.i. = approximately 13 H.P. It is not exact, as that is a sea level computation. The exact formula calls for a number of factors (not listed) that should also be taken into consideration, but not provided. improvement; There is no correlation between c.c./c.i to horsepower, For instance, a 250 cc motocross bike has about 35 hp vs. a 250 cc lawn mower engine has around 8 hp. The Briggs 205cc engine is normally rated at 5 hp. The 342cc Briggs is rated around 10 hp. There is a rough formula that some use as a general guide line; divide the c.c.'s by 40 and you will be in the ball park for a mower engine. So, 205/40=5.1 hp. In summary, your 205 c.c engine is about 5 horsepower. Kevin