I just joined this site, I think it's pretty cool so far so good. You might call me crazy! but I just built a 273 and installed a Crower Racing Cam in it, very close to stock spec.s I have driven the car for almost 1500 miles or so and I first clipped a sharpie pin lid to the bowl of the carb so the butterfly wouldn't shut all the way and adjusted the carb so it would always start up on a higher step of the choke fast idle cam. After about 2 to 3 minutes the choke opens and the engine idle's down. Great for breaking in the cam. I used conventional 30 weight non detergent oil and the oil is still clean, and everything sounds great! I just removed the sharpie pin cap and adjusted the choke and all is normal now. I will change the oil to Valvoline 20 50 Semi Synthetic as usual. I know it sounds strange, but it worked very well and back when they built these cars they were using this straight weight oil effectively. Also I did put a magnet right in front of the oil drain plug to release as I drain the oil.