You win some, you lose some, you regain some…

The title could describe a night at the casino, but it was more like a night of fun with valves.

You might get the idea that everything you grind of a cylinder head produces a gain. Well.. NOT !  I changed the back cut of one of the new style valves to a slightly wider one ( if some is good, more be better wrayght..!?), and simultaneously (aaargh.. note to self: never , ever, change two or more things at the same time) re cut the seat with a wider top-cut and a bit more down-cut.  The combination did not work well… I ended up swapping valves, blending tiny ridges caused by the new top-cut and down-cut and regrinding a margin on one of the old valves which had been slightly beveled as I had used then as protection for the valve seat while grinding chambers at some point. It makes a surprisingly large difference btw.

End result after all this effort was a tiny loss (after starting out with a big loss). One of the ”problems”  I have with this head  is that it started out as a MG metro head which has a special contoured bowl shape milled in which causes the bowl to be slightly bigger than the bottom edge of the seat. I really held back in fear of hitting water at the Siamese section

(head number one..) so that needs to remedied to see if that produces some gains in the upper lift regions.

that about sums it up.. luckily a Quik Flow is rather quick so the retesting does not take ages

Well children, what have we learned?. The upper-mid lift region is very critical with regards to seat geometry.. somewhere around where you are well into the cross over zone from seat to port .. low lift is pretty stoic and does not seem to affected all that much so far.

As the poet Jagger put it.. you can’t always get what you want.

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