5.7 0r 6.1 with msd hemi 6 and carb

From my experience when I had a carb on top of mine before I went back to EFI the timing seemed to be a little funky. I could throw mountains of timing in without ever hearing knock, but I think part of that was because my carb tune was on the lean side since I didn't have enough jets on hand to try to get it right. That's not saying that I was making any more power with the extra timing, just that it didn't seem to be hurting anything. I think part of the issue may have been that I was using a stock cam (designed for EFI) with a carb, so the carb may not have been getting the best sort of vaccuum signal. I think I bumped up the top end maybe 3-4 degrees from the base MSD map. It seemed to like it, though I never had a dyno to prove it. Most people that have put carbs on top seem to get away with the extra timing for some reason.