Speedex Heads

[Austin in the Shed]

In my case, Tom, 'out of the box' (although they don't come in a box - at least mine never have!). Dave's probably the best to comment about the potential for any modification. They're all numbered and dated. My latest version, bought in July last year is number 272. There's a lot of them around!

Steve

Compared to the original head I machine the valve area  and guarantee it will clear up to a 1.2" dia inlet valve with 5 /16" lift. I have reduced the turbulence step in the combustion chamber and raised the compression ratio to around 6 3/4 : 1.
The Ricardo is a 1920's design to use with the  fuel quality of the time.
They take nearly 4 hours to machine conventionally ,dress,inspect and pressure test.