This is strange. I have a 383 with about 40 min. of break in and 8 dyno pulls. When turning the motor over by hand it makes what I can best describe as a moaning sound from the cam area, best heard with the intake off. The cam bearings are new and show a smooth wear pattern on the lower half of the bearings. Springs are 450 lb. open pressure. If you back the rockers off or have low pressure springs installed, the sound goes away. It's also harder than I expected to turn over by hand. Cast iron core cam and tool steel lifters. I think its' too much friction on the cam journals and plan on polishing and maybe coating the cam. Anyone seen this ??