My Son Matt sold his .040 over 360 shortblock out of his Duster a couple of months ago to a Friend. Needing a set of heads for it I have been researching ways for him to get the engine assembled and into a Dart that he recently bought. Knowing the Procomps (Speedmaster) had some issues I tried to find some info on the ProMaxx small block head that Jegs sells. With springs good for up to a 575 lift cam they cost slightly over 1400.00 a set shipped, app 200 plus dollars cheaper than Edelbrocks. I told him if he bought a set I would flow test them on my bench and strip on down to check it out for free. So far I have nothing but GOOD news for these heads and they put the Edelbrock heads to shame in both quality and flow numbers. The only issue I see so far is that the exhaust port flows almost EXACTLY the same as the Edelbrock head and they both have terrible (slow) air-speed on the exhaust side. He is going to install these as delivered so I can't wait to see the results. Air-speed at .500 lift on the exhaust port maxed out at 175-180 FPS and I good exhaust port should be at least 325 FPS and needs bell-shaped to get there. Both exhaust ports maxed out around 182-185 CFM and were checked without a ex flow pipe
As you can see by the numbers this BOTH ports need more volume. The air speed on the ProMaxx at the pinch at .400 lift is 300 average (center) at the pinch and 370 on the pinch turn. At .400 lift 365 FPS-390 FPS on the short-turn. At .500 lift at the pinch center 340-350 FPS and 401 FPS (pegged my gauge) at the pinch turn. At .500 the short-turn is way high at 390-401 FPS (pegged). So far 4 valves were removed and the valve guide clearance is GREAT and a very nice at least 4 angle valve job done. The stainless valves look nice and come with a 30 degree backcut. I will be buying a couple sets of these later this year. One set with stock 2.02 valves and one set bare so I can go with a 2.08 valve
