Originally Posted by Morgan22
Thanks Bogie, I was hoping you would chime in on this.
I don't want to date myself but I remember when factory roller cams came out. The rumor was that the cam profiles themselves didn't really change much from the flat tappet profiles and the gain was really only in the reduced friction of the roller lifters compared to a flat tappet. Don't have a clue if that was true or not but that is what I remember.
I will try to use the factory roller set up and see if I can find a grind to fit my 393 combo in the 1500-4500 or 2000-5000 range with about 10 to 1 compression ratio. I live in the Rockies at 5000ft so I think I can push the compression a little more up here. From here in the city you can drive to the top of the mountain just outside of town and go from 5000 to 10,000 ft in about 10 to 12 miles. Pretty dramatic change in engine performance.
At the valve there wasn't any significant change in lift or timing. The roller served two purposes:
First was to provide (or maintain) existing durability compared to flat tappet cams against the reduction and final removal of high pressure organic metallic lube from engine oil such as ZDDP. This was done to enhance catalytic converter life.
Second was a side benefit where the reduction in friction between the lobes and lifters provided a bit more power but more importantly for the factory improved fuel mileage, which the Feds grade them against, so called CAFE "Corporate Average Fuel Economy" standards.