Heat Exchanger to head nut torque Options

[jmalone]

Can anyone confirm the torque figures for the heat exchanger to head nuts? I have initial torque at 7.3 ft/lb and final torque at 24.5 ft/lb.

[stugray]

I just went through this entire process:

1 - replaced all exhaust studs (Manufactured my own 8mm studs before removing the old and found out that all of my stud holes had been tapped out to 9mm).
2 - ordered new 9X8mm step studs from www.belmetric.com
3 - extracted all old studs with stud extractor tool from Sears ( the kind that pound on over the studs and acts like a bolt head)
4 - Installed all new studs to find that they all have a slight bend to them, so they need to be clocked right or the HE dont fit over them
5 - threw aside the stupid copper plated exhaust nuts from pelican parts because the flange on the bottom of the nut would not clear the side of the HE stubs. (actually accidentally bought TWO whole bags of them - anybody want some?)
6 - Bought 8mm "JIS Nuts" from Ace. They are smaller barrels so a 12mm socket will fit.
7 - Used SS washers under nuts (some had to be ground to fit in the small space)
8 - STILL had to grind off the side of a 12mm 6 point socket to have enough clearance from the side of the HE for the socket to fit down.
9- torqued all nuts to 14 ft-lbs
10- installed second set of nuts to lock the first set in place.

If I could have found SS JIS nuts, I would have used those.

HTH - Stu

[nathansnathan]

I just went through this entire process:

1 - replaced all exhaust studs (Manufactured my own 8mm studs before removing the old and found out that all of my stud holes had been tapped out to 9mm).
2 - ordered new 9X8mm step studs from www.belmetric.com
3 - extracted all old studs with stud extractor tool from Sears ( the kind that pound on over the studs and acts like a bolt head)
4 - Installed all new studs to find that they all have a slight bend to them, so they need to be clocked right or the HE dont fit over them
5 - threw aside the stupid copper plated exhaust nuts from pelican parts because the flange on the bottom of the nut would not clear the side of the HE stubs. (actually accidentally bought TWO whole bags of them - anybody want some?)
6 - Bought 8mm "JIS Nuts" from Ace. They are smaller barrels so a 12mm socket will fit.
7 - Used SS washers under nuts (some had to be ground to fit in the small space)
8 - STILL had to grind off the side of a 12mm 6 point socket to have enough clearance from the side of the HE for the socket to fit down.
9- torqued all nuts to 14 ft-lbs
10- installed second set of nuts to lock the first set in place.

If I could have found SS JIS nuts, I would have used those.

HTH - Stu

It is debatable, but stainless exhaust hardware is probably not as good as regular steel. Stainless expands more with heat so they are more likely to loosen over time. It can gall both itself or regular steel more easily. Also, unless you use ARP nuts, typical stainless nuts are probably equivalent to grade 3 .

The problem with using 2 nuts on an exhaust stud is that you can't reach the 'inner' one to hold it from turning taking the exhaust off, and the 'outer' one will want too drag it, ruining the stud thread.