[quote=fast68plymouth]While I see many people posting how "normal" home port jobs on
OE iron heads can easily flow 260-270-280+, the fact is, those
cases are few and far between. The typical big valve 906/915 type
BB head that was home ported or not done by a shop that is well versed in
preparing racing heads usually flows in the 240's, or less. It's takes
a fairly skilled person with a good understanding of those heads to
get them to flow in the 270's +.
This is one of the main reasons heads like the RPM's and Stealths
so often outperform ported OE heads without any additional work
done to them. The home ported "260+ cfm" heads aren't usually as good
as the owners think they are. Unless they have been on a flow bench,
you'd really just be guessing.

Here are some numbers from some recent heads that came through
my shop for freshening/updating. Neither of these sets of heads were
home ported, but done by a regular machine shop that wasn't necessarily
specializing in head port work. They had the usual big valve install
and some amount of associated blending along with some blending
of the pushrod pinch area.

Very true. The areas of the 906 casting that need work to get the CFM in the 260 + range are kinda hard to get to. Then when you start getting real good number you cut through the short side. The numbers you are posting reflect the numbers that I get on my bench. So far the best 906 that I have tested was 300 CFM. The short side was flat as a board. No idea how they got that lucky.