SOTP Vintage Series
Main Motorcycle: The one between my legs
Join Date: Feb 2009
Location: Upstate NY
Other Motorcycle: A few
Extra Motorcycle: Yes
A shrink fit spigot is an interesting fix. If this subject has been discussed before, please excuse the question and just tell me to do a search.
Norton's apparently are notorious for beating out the threads on their exhaust ports. I realize it is not a spigot, but rather a nut config.
I sounds like fitting a shrink fit spigot and using a clamping arrangement would be a better fix for a Norton than the welded in bushings, which I understand are known to fail. Have you tried this fix on a Norton and was it successful. Not sure there is enough meat in the head to do this, but might be worth a shot if there is.
My '66 T120R has an iffy thread on one port. I'll definitely be fitting the later style header supports. Might need your spigot fix at some point.
For those desiring originality, why not fit the original cross brace support as well as the crank case supports. Chances are, a judge might give you a pass since you have the correct brace and are using the later braces for mechanical integrity.