you need to degree your cam in. I put mine in at 108 in my 340 that was right around 10.5:1 and had about 150 cranking compression. It liked the timing to be locked out at 36* and I could get about 9 to 11 inches of vacuum out of it, thats the only way it ever ran right. In small blocks, that cam likes the timing to be locked out. and if you never degree your cam, you'll never know where its at. dont go by "half a tooth off" buy a cam key set, and put it where you want it. anywhere from 108 to 104 is ok with that cam.