69 - 427 Firewall Clearance
While the engine was out I repaired a hole in the AC/heater box/firewall (using fiberglass repair kit) that has been there since the we got the car 34 years ago. I figured this was also a great time to replace the engine and transmission mounts and as I learned hard way it affected the fit of other things like the after market headers that have been also been on the car since we got it. I did not measure the distance from the #8 cylinder pipe to the AC/heater box before but after the everything was back together is looks closer than before and once the engine gets to temperature we see/smell smoke. We have replaced the electrical engine and dash harness and all is good there so nothing electrical. The car came with AC but that was removed 40+ years ago by the previous owner and we have all the resistors unplugged. Can anyone recommend a minimum distance between the header pipe and firewall/heater box or if I should have used different material other than fiberglass? Is there some kind of sealant or protective paint I should have used? 