Kris..The url is down, less there than what I just said here...
Timing is the option of the buyer, mechanical link, syncro spark, or fixed..They all get to 28 degrees BTDC at full throttle, Just at different times..Mechanical is linear, direct connection to the carb..Syncro is electronic, full advance at 4000 rpm...Fixed is just that..Small engines under 3 cubes don't really need any retard for starting....