I noticed a few days ago that my 328 was making more exhaust noise when it was idling. It sounded normal at higher rpm levels - pretty strange. I looked at the exhaust system and found that one of the brass nuts holding the forward exhaust header to the head was missing. The local dealer didn't have the required brass nut or brass gasket in stock so I sourced them from Ferrari UK. Neither the 328 nor Modial 8 service manuals list the torque value for the brass nut. What value should I torque the nut to? Also - do the brass exhaust gaskets need to be replaced each time the header is removed or just if they're damaged? Thanks for the help, Jim V.
Six years later, I'm wondering the same thing .... can't find it anywhere. Would anyone have this info at hand?
Cant tell you what Ferrari says but if you tell me the thread size, I can look it up in my engineering handbook. The brass nut is probably the limiting part in the stack up. I imagine the stud is steel. I can look up the torque range for a brass nut if you want. It would give you a pretty good idea of what it should be. FYI normal torque ranges are 80% of yield of the weakest part in the bolt, nut joint. Head bolts etc are special science but everything else is pretty standard.
The tricky part is figuring out just how much torque you are applying with your special cut-off open end wrench while having your arm fully extended and using 3 fingers Pulling the stud out of the (Aluminum) cyl head might also be what fails first (so don't do that).
