Timing or the starter?

[68 ReNay]

I recently put a small block stock, crate motor in my '68. i'm having difficulty getting the right timing. when i set it at the standard 10-12 degrees, i have now power (smoking the tires, etc). but it starts everytime, hot or cold and drives fine.

when i advance the timing enough to get the performance, smoking tires and second gear scratch, then it heasitates to start when the motor's warm - like driving across town and stopping at a store for a few minutes. once cool, it starts right up. so it initially sounds like a case of Heat Soak on the starter, but this never happens when the timing is retarded back down to say 11 degrees. i can drive it for an hour, turn it off for a few minutes and it starts right back up.

what's going on?