potatoe

hello. i have read instructions and watched videos of how to do it on youtube, but i cant seem to get it to go into base timing. or possibly come out? nothing changes when i jump the two white wires from distributer. i notice in the video of the change it makes, and runs choppy when put in base timing. also in order to get it to run good and normal, i have to put the distributer around 12-18 degrees btdc. is that where it goes when advanced? i have it running fair, but i cant get it to the 1 degree btdc like it is supposed too because when i do, it skips and runs crappy. does anyone have any advise? is there somthing wrong with my distributer. thanks
boat is a 2002 bayliner capri 175. the current owner purchased it new and after 2 summers, it was not winterized properly and he paid the price with an almost brand new block with a huge crack in it. i got a deal on boat, and replaced block head and manifold from 1987 mercruiser 3.0. everything else was from 2002 engine. 87 had conventional ignition. 2002 had electronic est ignition.