any one help me on some ignition elec. advice?

im trying to wire a 440 in a street rod,, it willl turn good in the start position but wont start till i quit trying to start it and let the swith spring back to the on position.... if I direct 12v to the resister, she fires up right now... seems im not getting 12v to the resister while the engine is turning... I think i need to get full 12v to the coil while it is turning over...any ideas for me???? thanks in advance

mel