- Dec 10, 2008
Rich_j said:comnoz said:Wit stock aluminum threads there is probably a small advantage in using the bronze nuts because they expand at a rate similar to the aluminum head so they tend to stay tighter. With the bronze inserts I would stay with steel nuts to avoid the friction caused when like metals rub against each another.
An interferance fit means the insert is slightly larger than the hole it is being screwed into when they are at the same temperature. To make it fit I heat the head and cool the insert before I thread them together. Locktight sets up very fast when it gets hot . Sometimes faster than I could screw the insert into the hole. Then I ended up having to bore out a half installed insert that wouldn't move anymore and starting over. There is no such thing as overkill when it comes to keeping an exhaust attached to a Norton head. Jim
Is there a reason why you prefer an interference fit and JB weld rather than key locking ?
Yes, It's because I have seen a few heads that had key locking show up with cracks starting at the thin section next to the key. I have had no problems with the inserts coming out with-out the key. Jim