This picture shows the indicator plates fitted to the front face of the valve chest. The soft aluminium plate on the top is used to scratch marks showing the valve position at certain wheel positions. This is how the valve setting is measured.
This picture shows the indicator plates fitted to the front face of the valve chest. The soft aluminium plate on the top is used to scratch marks showing the valve position at certain wheel positions. This is how the valve setting is measured.
Credit: S.Masters, 4/12/16