I pull in a garden stock class and use a 12.5 hp B&S vertical shaft flathead motor. The tractor is branded "Co-op", but it's a 1980's model Gilson-built machine. It's belt driven with a 4 forward speed with reverse transmission. I don't know the make of transmission, but it has a heavy cast iron housing. The gears are completely stock. The tires are 23 x 10.5 x 12 un-cut Carlisle Super Lugs. The motor is pure stock with the exception of having an 11 hp (25 c.i.) head and un-muffled header pipe. The two piece carb is un-modified as well.
I said all of that to preface some questions:
1) Could I expect the use of a fly wheel key to advance the timing to cause a noticeable difference in the motor's performance on the pulling track?
2) If I were going to use such a key, which one should it be? I've seen suggestions anywhere from a #3 to a #7 on various racing posts on this sight?
3) If I elect to use an advanced timing key, is installing it as simple as removing the flywheel, installing the key and re-installing the flywheel (assuming no other changes to the motor will be made)?
4)Is it possible to put the key in wrong?
5)Will the multiple anfgled valve grind described in Don G's Motor Building 101 dvd advisable in my case?
Thanks for reading this; I look forward to your responses.
Mitchell