Today the long awaited fitting of the middle cylinder valve liners, took place.
The liners are machined to be a very tight fit in the valve chest bores, so they are chilled in liquid nitrogen at minus 200 degrees C to shrink them and allow them to be slid freely into place.
The upper photo shows a cannister of liquid nitrogen that has just had the rear liner placed into it. The relatively hot liner at 3 degrees C causes the nitrogen to boil (hence the fog !) until the temperature of the liquid and liner balance out. The liner is then lifted out of the cannister, checked for size, re-immersed to ensure that it is as cold as possible, then fitted very quickly into position.
After about 4 minutes, although still very cold, the liners have warmed sufficiently that they cannot move in the bore and after several hours will be very tight indeed.
In the lower photo, looking from front to rear, the liners are in position - the extreme cold causing moisture in the air to freeze as it touches them