I've been trying to tune my BC Rochester on my 63 Nova and have not been able to prevent an off idle stumble, hesitation and occational backfire. The accelerator pump is good and I've adjusted everything to factory specs to no avail. One other question, does anyone know if the automatic trans carb's throttle body has a hole or slit inside the vacuum port for the distributor/trans? My carb has a slit and I think it might need the hole to give the distributor/trans full port vacuum. Any help would be greatly appreciated.