29-09-2018, 03:35 PM
30 ml is about right for a sports head. You could kill the meniscus with a spot of fairy but it may give you a froth problem instead!
If being fussy you could subtract about 1.3cc for valve head intrusion and add 3cc for head gasket thickness (assuming 25 thou compressed).
Do your pistons stroke to top of bore or stop 20 thou short? Are both valves fully closed at bdc on inlet?
6:1 is a nice figure for a reliable road going car. I ran 10:1 in my youth but figured it couldn't last...
In my experience quoted figures often ignore the head gasket.
If being fussy you could subtract about 1.3cc for valve head intrusion and add 3cc for head gasket thickness (assuming 25 thou compressed).
Do your pistons stroke to top of bore or stop 20 thou short? Are both valves fully closed at bdc on inlet?
6:1 is a nice figure for a reliable road going car. I ran 10:1 in my youth but figured it couldn't last...
In my experience quoted figures often ignore the head gasket.