What happens if there is too much clearance?

• If there is too much clearance, the valves will open late and close early. ‘Knocking effect’

• The valve opening period is very much reduced

What happens if there is too little clearance?

• If there is too little clearance, the valves will open early and close late.

• There is a likelihood of the valves not closing fully and lead to leakage of combustion gases.