I had the same problem last summer(it was hot like this year). Made me nuts. After some failed fixes, this is what made a difference. Point gap was a bit small. A dwell meter helped find that. The needle was sticking a bit(some 600 paper polished up the sides and let it work with modern fuel) and last.. the power valve was sticking. Again some 600 paper polished it up and made it free. After that was done the timing was different so I needed to retard it just a bit. Problem gone. You might have different issues, but this worked for me. The above posts are good ones. That "new" B is very much like the old one I have. And, the 64 230 runs a bit hotter than my 235 so the tips on fuel heat matter. Let us know what you find and what works. Lots of helpful folks in here.
