Old Britts – Tightening the Exhaust Nuts on a Norton Commando
Download the complete PDF version using the green download button at the top right of this page for an Old Britts technical article covering a proven method for keeping Norton Commando finned exhaust nuts secure. Written by Fred Eaton, this guide explains why loose exhaust nuts are a serious problem, how they can damage the threads in the exhaust ports and what hardware changes help improve long-term retention on both street and race machines.
The article recommends using the later 850-style exhaust nuts where appropriate, together with good squash washers, rather than relying on the earlier lock washer arrangement. It then explains how to drill small safety wire holes in the exhaust nut fins, apply oil or anti-seize to the threads and tighten the nuts firmly before heat cycling the engine.
The final section covers re-tightening the exhaust nuts after the engine reaches normal operating temperature, then safety wiring each nut to the lower rocker cover nut. The article includes practical routing notes for the safety wire and photographs showing the finished arrangement, including how the wire can still allow rocker cover access without being cut.
Contents Include
- Why loose Commando exhaust nuts damage cylinder head threads
- Using later 850-style exhaust nuts
- Recommended squash washer use
- Drilling safety wire holes in the nut fins
- Warning not to drill into the cylinder head fins
- Applying oil or anti-seize to exhaust nut threads
- Initial tightening and heat-cycle re-tightening
- Safety wiring the exhaust nuts to the rocker cover nut
- Wire routing guidance and finished examples
- Maintaining tappet access with the safety wire in place
