massive reconfiguration time again.
Same style I've always used I didn't know I was doing something wrong...
The subject is tuning these carburetors and I believe I have the time in close enough.. I already bumped it up to degrees like you mentioned before and it brought the timing on the strap way too close to the base.. and there was no improvement in the hesitation. Actually tried to Buck a little under a hot start and I just put it back this last time I pulled it out... I'd rather just get on with trying to get these carburetors right.. twisting that distributor back and forth it's too simple. Getting these carburetors to run properly is becoming a bit of a bear...
It's not the wrong plug. I use the short reach plug sometimes if I have something like a Hemi or some of the BB heads where the cool intake charge blows right over the plug when the intake valve starts moving off the seat. The long reach plug has more exposed area, and the temperature drop can cause the plug to show being rich, when in reality it is lean. Switching to a short reach plug helps stop some of that.
So sometimes you can get fooled by stuff like that. The small block heads have a much better plug location than most of the BB stuff, so the reach isn't an issue.
I have no doubt that you'll get the carbs in shape. I saw a tuning flow chart in high school (should have kept the the thing) and it showed the interrelationships between timing and the ignition curve, engine verses RPM, plug selection and carb tuning and how they all worked together or against each other.
You may make a change to the carb(s) that ends up calling for different timing, different heat range of plug or design or a combination.
It's almost as much an art as it is a science. That's why it's interesting. And frustrating!
Edit: BTW I forgot to mention this, which I'm sure you know and understand, but others watching this thread may not so...if the engine wants more total and you give it to it, but it kicks back or bucks on hot starts, you need to either slow the curve down (some guys set up their curve so as soon as the engine sees any RPM over cranking speed it starts adding timing) or change the curve a bit to reduce the intial (add mechanical advance) while keeping the total where it wants it.