Inlet valve 2cv6, 'one piece', 'rotary' (see tech. notes) 2CV RACING CLUB UK spec., machined for better gas flow. SEE NOTES.

40mm head, 8mm stem, 88.5mm length.

In fact these valves are not one piece, however race customers expect them to be, the stem is a different material to the head because the two areas of the valve have totally different functions.

These valves have the stems waisted behind the valve head cause less obstruction to the moving gases.

This type of valve is classed as 'rotary', this is because the 3 collet grooves allow the valve to rotate slowly, gradually within the collet to avoid the same part of the valve head being in persistent contact with the same area of valve seat, due to the engine being air-cooled excess heat is more concentrated in certain areas than with a liquid cooled system.