Well, at the 330 cfm level, it definately isn't a street head! It is very thin all over. "Huge" intake valves, very tiny combustion chambers, this also unshrouds the intake valves unbelievably well because the chamber is so shallow,you will see a big jump in flow by doing this. But compression will sky rocket. Also, keep in mind, to achieve this level of flow and HP, you need to make the bowl area at least 85% of the size of the valve you are using, and this should be machined and not ground with a grinder. Also,a 2.02 valve will still be too small to see those kind of #'s. And finally, if you do all the above mods, this last step is the most critical and very important, and if you don't do it,not only will you loose valuable flow and HP, but potential engine damage can occur. Because you have now made the head so thin and flimsy, by decking it so much and removing so much material from the ports, and removing the head bolt bosses, and heating to apply brazing material, you absolutely have to do the valve job with a torque plate bolted to the head. It distorts so much when you torque the head to the block if you dont, that the valves wont seat. Even pulling the head between rounds at Indy and other races, I had to put the torque plate on it just to lap the valves, its that critical. Much of the epoxy and chamber brazing you saw with the head Kirby has is most likely a repair. We were constantly having to replace the entire combustion chambers on several ports, because the head was milled so much and the deck was so thin, the compression so high, the chamber would seperate from the head entirely. I've often wondered what the practical limit would be for those heads as far as flow goes for the street, having a good reliable good flowing head and not having a time bomb. 280...300 CFM, I've been thinking about doing another one on the conservative side, just to see, since there seems to be a lot of interest in these engines growing.
