All due respect, are you saying that you can not rework a set of stock heads 4.0 or any heads for that matter because you can not find stuff on a shelf at Summit, Jegs or any other so called racing supply house. That you can not put a set of heads on a flow bench and not make them better and most instances much better. Lets say the other parts like headers, manifold and could be had. The only thing left are the heads and no one carried after market HP parts. Do what hot rodders have been doing for years. How about a porting job, that does not take any after market parts, How about a multe angle valve job to increase flow around the valves, reworking the back side of the valves for better flow, turning down the valve stem between back of valve face and valve guide for better flow and to reduce reciporcating mass. cc'ing the com. chambers, reworking the valve pockets, shimming the valves springs for higher spring rate if possable. How about removing a few thousands off the face of the head for higher comp. Just because some well known vave co. does not make larger valves does not mean nessecarily there are none to be had. Case in point, I wanted larger valves in my 5.0 heads. I did not call Manley valves I just went to a chevy dealer got their 2.02 or I could have used ther 1.96 valves and use them for my intakes. With some research there might be larger valves from other engines that might work. This is what I mean by basic hot rodding. Now with that said put those heads with the mods. listed and put them on a flow bench. Maybe the things I mentioned can't be done to a stock 4.0 head but I surly would not write them off. I'm glad those boys of the early 50's and 60's did not give up because they couldn't buy their parts from a shelf. That reminds me look at the back of my t-shirt post (under the sun)
