Joined: Aug 2017 Posts: 524 Threads: 84
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How much clearance does a valve need at full lift in the combustion chamber ?
For the best flow should there be a good clearance above the valve or not ?
Joined: Aug 2017 Posts: 1,265 Threads: 33
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Location: Cheshire
Car type: Race Ulster, 1926 Special, 1927 Chummy, 1930 Box
Ideally there should be space above the valve, but in reality there is probably more benefit in maintaining a good compression ratio. I usually fit the head without a gasket. If the valves don’t hit the head, it should be ok with the gasket fitted.
Alan Fairless
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For optimal flow you just want it as far open as possible. I agree with Alan, as long as it's not physically touching the head you should be OK.