When Norton patented a four-cam desmodromic valve system for its Manx race engine in 1957/8, they had neither the time nor resources to realise its full potential.

The owner of one of these legendary machines approached us to get it performing as intended after previous specialists had failed. Even for the expert Crosthwaite and Gardiner team, it was a challenge.

But we thrive on challenges, and we have the intellectual horsepower to match our engineering capability. So, with no original drawings or data or to work from, our design engineers made new cams, rockers and rocker shafts, and applied modern material coatings to maximise their longevity.

Having extracted the data for the opening cams from the remaining sample, we calculated the profile and correct operating clearances of the closing cams in order to return this rare and historically important engine to the customer completely rebuilt and ready to race.