ORIGINAL: navav2002
Do you use an articulated header?? (P.S. "Articulated" is not my term..he he..I'm stealing it from somewhere else...lol...I'm not that smart...Hummm..Did I even spell it right?? ..Oh well...)
I have had them crack both ways (Articulated or not
). The 2 major reasons I found for this "cracking" was:
1.On the fuse top style headers from Mac, the pipe is cut on a angle where it meets the header flange. The pipe itself would hang over the header flange at the bottom and would be filled in with "weld" to fill the gap. On mine the crack would start at the joint in one of the corners where the pipe over hanged the header flange and work its way around do to a lack of "weld" in these areas.
2. The header flange face was not flat (tweeked) where the flange would meet the exhaust port on the engine itself. When tightening the header screws.... it would stress the flange/weld and the slightest amount of vibration would cause the header to crack at the joint. Keep in mind too.... these were new headers bought and used "back in the day" So this doesn't mean that they have this problem today. I have not bought any in a long time due to having a stock of them.