If there is a crack that only opens when it is hot, it isn't the problem because it doesn't run right when started from cold. no noticeable difference when it gets hot.Jerry, I've been working on multi carb engines for more than 50 years. Most of them factory.
They do work very well. Take the early Corvette with the inline 6 and multi carbs. It cruised along main street on Saturday nights just fine.
