new build no spark no start

well still figuring out the problem. i can take the dist. out and turn it by hand and gets plenty of spark. but when in and turned by starter no spark, power at coil will drop to say 9.8ish. i did get her to spark a few times with a fresh charged battery but didnt last long. i will be trying a lil bigger battery but starting to think i need to step up to a hi torque starter. it is currently a mini starter for a 93 318 dakota from napa. there is alot more compression in the new motor.10.5 the starter sounds like its movin fast enough.

when turning the dist. by hand while out of the car it sparks only when its moving at say 400 rmps nothing if you go slower. (the 400rpm is just an example).

oh ya its a msd blaster2 coil w/ a digital e curve dist. it calls for a 12 volt source and i have always had trouble starting the old motor with a week battery. the ballast is bypassed.

anybody any ideas why this dist dont fire at low speed.