96 s10 blazer 4.3 won't start

[JWOLVES]

i have a friends blazer they tried to replaced the distributor and can't set the timing on it i need help and maybe a diagram on how to set and where the timing mark is on the distributor i set it in between the 2 and the 4 wire on the cap this is self timing do i have to unplug a wire or something to reset it it will not start and i'm about to replace the timing chain and gears can anyone help thanks