<VV> Hard Start

[JAY BOTWICK]

I have a 65 Corsa Convertible 4 Carb.
When I first start the car it turns right over.
Every restart as the day goes on gets harder and harder to the point that after the 5th or 6th restart of the day it won't turn over, with a jump I can get it going.
Usually happens with short trips throughout the day, especially in hot weather.
After sitting overnight the engine turns right over.
The hard starts sound like the battery is dying but I've had the battery checked and it's fine.
Any thoughts?
Thanks,
Jay Botwick