VALVE GUIDE
Guides guide valves and cools valves by conveying the water accumulating around valves to cooling water.
The hollow between guide and valve is important. If the hollow is wide, valves run hotly and deform. If the hollow is narrow, valve is stuck by valve due to expansion so hollow must be adjusted accurately.
Worn guides let lubricant get into the combustion port and blue gas emits through vehicle exhaust.
MATERIALS USED IN VALVE GUIDE
G : Pearlitic grey iron with good resistance to wear, suitable for applications with normal stress levels.

G1: Pearlitic grey iron with added phosphorous, which forms a lattice significantly enhancing resistance to wear even when lubrification is poor.

B: Alloy with high resistance to wear, good resistance to fatique and corrosion, suitable for applications with medium stress levels.

B1: Phosphor-bronze alloy combining high resistance to wear and high thermal conductivity with good anti-friction properties, suitable for applications with high stress levels.

S03: Tin/phosphorous alloy with good mechanical resistance and good self-lubricating power, for excellent wear resistance to glide under the severe working conditions typical of engines of the latest generation and high performances engines, fueled with petrol, gas-oil or gas.