In a nutshell....... what he did for the first few steps...... that’s where the good “bang for the buck” ends.
As I’ve mentioned in other threads........ getting these into the 260cfm range, at a reasonable/usable lift...... should be pretty straightforward.
Recut the seats, blend bowls, back cut valves.
That’s where the cheap n easy gains end.
My attempt at the next step up from there, which would strictly be aimed at improving the numbers through .500-.550 lift or so, and might even cost a cfm or two at the top end(for the same reason that PBR had his last test do it)...... I’d go to the 2.055 intake valve(I’d buy bare heads if this was the plan from the beginning).
In all likelyhood though, even that change would probably require a bit of short turn work to make it worthwhile.
My goal would be to get into that 260 range with even less actual grinding than PBR did.
No(or at least less)work at the pinch and bolt boss..... and hardly anything in the bowl....... and little to no sanding.
I’d be relying on the bigger valve to relieve me from more grinding.
