The 500cc engine CODE 12 , This engine family was
twin chain with magneto and dynamo. It is used in 49-52 plunger and 53-55 swingarm model 7and were also used in limited hardtail production.
The "Norton brand" Lay down gearbox was used on all model 7 bikes
Here is another forum, started in 2008, specifically for gardengate Norton heavy twin the
model 7started in 2008
https://groups.io/g/nortonmodel7
