Classic/Antique Car Repair: starting problem !, torque starters, summit racing

Question
hi.  i have a 66 gto, 389 bored to 409, ram air 4 cam, comp-10.5, headers, and 750 rochester.  the car runs great and strong, till i turn off, at which time the battery just about turns the engine over.  i have replaced with much larger draw amperage batt. and still same.  i have even gone to the extent of adding another battery in trunk, paralleled the wires, and have cured the problem a little bit.  at least it will turn over to start. i also have taken asbestos tape and wrapped the headers at the point they pass the starter, thinking i could reduce the resistance, due to the heat.  but no.  what do you think.  thanks

Answer
Summit Racing and a few others in the hot rod market sell High Torque starters. With a compression ratio of 10.5:1 this will probably be your best solution. I would also check the charging rate of your alternator to be sure that you are completely charging the batteries. When the batteries are fully charged and the engine running at 1500 RPM's I would want to see a voltage across the battery as close to 14.4 volts as possible but no less than 13.5. If you have a mechanical regulator, it is adjustable.