I have a ford aod which uses the same principal....has a tv cable from the carb to the tranny..........when i built mine the first thing i did was get a lokar tv cable so i could adjust it up top by the carb.......my tranny is modified so might be a little diffrent then yours but.....my first.second gear will not shift when i am manual shifting until i do so..........when i am in drive it shifts by itself at 5500 rpm........by adjusting the tv cable it will shift harder,faster and will shift at 6000 rpm haven't adjusted any higher then that as it will shift like way to hard break your neck...............but if you are loosening the adjustment it will shift earlier,slower and if to much will burn out the bands in a short period........i lean to setting it higher( i set mine with a pressure gauge in a port on the side of the tranny and shorting the adjustment gives you more throttle pressure and will make it shift harder,faster and higher rpm...................i hope this helps as mine be alittle diffrent then yours but close .............i would not fool around with it if u r not sure take it to someone that knows