Just returned from my latest road test and got a discouraging 19mpg at 70mph. After a little thought I'm coming to the conclusion that the Crower 03340 (with 240HDP 114 deg grind) is not producing the economy that I hoped it would. Last Summer's road trip produced 20-22mpg on the highway with a Comp Cams 252H grind (206/206 [email protected]; .425/.425 lift@valves; 110 sep) and I had hoped that the milder Crower (182/190 [email protected]; .386/.287 lift@valves; 114 sep) would produce better low end torque and superior mileage. Sadly I have yet to see the engine break the 20mpg barrier and have seen 17-18mpg on most of my highway runs. I have replaced my Proform HEI with a Performance Distributors' DUI, had the carb rejetted with a wide band 02 sensor and did what I could do to eliminate other potential problems. My only conclusion can be that either the 1.52/1.60 rocker ratios are the source of the problem or that the Crower isn't doing the job I purchased it to do. I'm guessing that the Crower 03340 may have been designed for a fuel injected engine (which the majority of 4.3 V6s have) and may not work well in carbureted applications. I will probably swap to another cam next Spring.