Originally Posted by
pa_sjo
.. I think you'll find the inlet valves are a different size too.. Try putting both heads side by side and doing a proper comparison
Which is exactly what I did over 3 years ago.....
Your forgetting that the valve sizes were increased from the Silver top in the Black top engine. I apologise, the ST170 inlet valve
is 0.5mm bigger diameter.
Originally Posted by
pa_sjo
The only thing remotely similar is the size and shape of the exhaust ports.
As for being pedantic, not being remotely similar, I think is applicable to a comparison of CVH to Zetec head, not the subtle differences of the St170 one. Which as I said is a not too difficult swap. Many of the parts can also be used in a standard head. As an example, the solid top cam followers are a far cheaper way to go with high lift valves, than after market ones. Making it all work properly, as with anything, is another matter.
Martin