brass washers for manifold
Actually that is not correct. The factory nuts look similar to castellated nuts, but if you look closely the "castle" part is tapered on the outside diameter, and the "notches are much smaller. The taper/castle side goes on the stud, and seats in the taper in the brass washer. This squeeses the castle part of the nut tighter on the stud, This prevents the nut from comming loose, without having to overtighten the nut. The manifold cannot be tightened too much. it must be free to "float", otherwise it will crack.
PS: the "special" nuts are made of unobtainium. The brass washers are hard to find, also.If you find them in a salvage yard, grab them.
The brass washers are ordinary hexagon washers, for use on all studs except the top front and rear, which originally got castellated nuts. You can still get castellated nuts, see for example here
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Actually that is not correct. The factory nuts look similar to castellated nuts, but if you look closely the "castle" part is tapered on the outside diameter, and the "notches are much smaller. The taper/castle side goes on the stud, and seats in the taper in the brass washer. This squeeses the castle part of the nut tighter on the stud, This prevents the nut from comming loose, without having to overtighten the nut. The manifold cannot be tightened too much. it must be free to "float", otherwise it will crack.
PS: the "special" nuts are made of unobtainium. The brass washers are hard to find, also.If you find them in a salvage yard, grab them.