As delivered if ordered straight from Summit (Trick Flow), those heads are no where in the ball park of 360 cfm, seriously. I see them at 310 here at .500, which is really pretty good, and then 315 at .550, and then 307 at .600 as they scream back at you. Yes, they can be fixed not to do that, but as delivered, that is what they do here. The EMC head flows 302 here at .500, and 315 at .600. Same bench, same method, smaller valve. The low lift numbers below .500 are tit for tat. I was thinking along the lines of streetable .600 lift cams when I posted what I posted. There is not much long term success on the street with .700 to .800 lift, which is where you would have to go to see 340 out of a TFS head on my bench, after fixing the short turn turbulence. That EMC iron head will not flow more than 330 here, even with the floors filled, at .800 lift. There is more high lift flow potential with the TFS or any aluminum head, just because you run out of real estate in the OEM iron casting. I was stating the facts as I have witnessed. I put those TFS heads on a 390 with two 600 carbs and similar cam to the EMC engine and it made 600 hp, whereas the EMC piece made 620 on that same dyno (BES at that time). So between flows tests on the same flow bench and dyno tests on the same dyno, I saw pretty similar performance between the TFS and the EMC iron head.
You have to consider how it will realistically be used, and spewing max flow numbers after further modification, at non streetable lifts, in an attempt to discredit my comments, is really not an accurate representation of how most people will use a street engine. The TFS people really did a pretty good job making an out of the box head with good .500-.550 flow. There are other things I don’t like about that head, but as far as mild cam streetable flow, that part is good.
I don’t disagree that the TFS head has more potential than a 60 year old iron casting. The original question was asking about iron heads. I just gave my opinion on heads as they would be received, from TFS, or from me. Not intended to spark any argument or controversy.