[Brian]

Combustion chamber design is possibly one of the most debated subjects when it comes to flathead performance...and I think it plays a very important role. The major issue is flow versus compression; to increase flow rates we need to open up the passage between valves and cylinder; in doing so we automatically lower compression. Also there is the heat conductivity factor of head material; aluminium, by virtue of it's higher heat dissipation, allows higher compressions with out spark knock, but the heat dissipation takes out some of the effect of the same cr in iron heads.
I've built numerous flatties, in varying styles during my lifetime. One advantage of building flatheads for customers is one can incorporate different ideas at customers cost, knowing, whatever one builds will run, but how well?
So. after untold expense [not all mine], I have sort of an idea as to what works in combustion chamber design. My favourite engine to build, for the performance gained is still the little 221....
I fully understand people, such as Ronnieroadster, wishing to keep their hard earned secrets to themselves, and I respect that immensely. Others, such as Ol Ron, freely give of the discoveries they've made over the years I admire what individuals such as himself, [and others] have achieved, but I'd like to start a discussion about cylinder head design.
What, in your opinion, is the ultimate flathead combustion chamber design?