Big V8s usually start easily even when cold. If it has an automatic choke I think your auto choke is not closing enough in some types
of weather. Are the no-start days during the same kind of weather? Some days are not quite cold enough to close the auto choke completely. Most chokes need to be completely closed on the first start even in warm weather.
Before your first start in the morning don't turn the key to start, push the accelerator pedal to the floor,release it, go out and remove the air cleaner, check to see if the choke plate is closed. If not closed, hold the throttle open at the carb, push the choke plate closed, release the throttle, go back inside and turn the key to start. If it starts you have found the problem. It is either hanging on something or needs adjusting. Auto chokes usually need to be adjusted for different conditions.
Another possibility is a bad condenser. This exact thing happened on my 225 slant six but it was hard to start every time if it was allowed to sit for more than an hour.
