Hey all, I have a fresh built 391 in a 72 Newell Motor Coach with a Holley Sniper EFI and Hyperspark Ignition. Ignition timing is currently set to 10 degrees and I'm about to adjust to 5 in hopes of it helping. It only overheats when sitting idle. New fan cluch, new custom shroud, radiator was cleaned. I'm thinking Ignition timing and maybe the radiator cap is the wrong psi. Any 391 guys out there that can help? I've made 4 trips in this Newell since I restored all of it and it really only gets hot when sitting idle after a long drive. What should I be looking at as far an Ignition curve?