Just in case anyone is interested, I have the flow figures from when my Holbay head flowed. As far as I am aware, it had not been messed with and is 'as per factory' The flow figures aren't that good TBH, and unfortunately all the cooling and RR gear was long gone.
This is what I have for the Holbay head @10 inch (x1.58 for 25").
inlet
lift .05 .1 .15 .2 .25 .3 .35 .4 .45 .5
17.8 34.7 52 70.5 84.4 90.8 96.1 100.6 105.3
108.7
Ex
lift .05 .1 .15 .2 .25 .3 .35 .4 .45 .5
13.6 27 39.7 48.9 57.9 66.3 71.8 75.2 75.2
75.2
Shaun
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