Originally Posted by TommyK
I think you may find that your starter has less tolerance for initial timing in August than it does in February. Might have to repeat this procedure on a really hot day after the engine is really heat soaked.
That is because excessive heat can lead to "pre-ignition" which is the same a over-advanced initial timing. Over advanced ignition causes the piston to compress the ignited mixture, making the engine difficult to start.