Looking for help or ideas to seal headers to heads. I have a set of modified 452 heads on my Road Runner's 440. I recently replaced my headers with a new set of Doug's. During replacement, i found that the threads on the driver's side head were pretty far gone. Through the advise of a friend I reluctantly heli-coiled the header bolt holes. Since repairing, I have been unsuccessful in sealing the coolant. I do not have enough room to run studs. Any ideas on sealing the leaks?? I've tried pipe dope, and even silicone RTV. The RTV seemed to seal better than the pipe dope, but I still have a trickling leak. Tom