what could cause this ???
in my 383 stroker (5.7 Rods) scat crank, clearanced rods, using a Summit cam# sum 1103. It had a wierd "rapping noise" in the engine since I installed this cam,(didn't have it with the previous Comp Cams cam). was loud when cold & almost go away when it warmed up. I figured a lifter. (they're new) but when it was cold & I drove it next to a concrete wall, it almost sounded like a rod knocking ! but went away when warmed up. (& holds Great oil pressure even when hot). ANYWAY, I pulled the cam today to check it for worn lobes, there is nothing wrong, (all the same lift) BUT...the 7th LOBE back from the front (#3 exaust) looks like something HIT it FROM THE SIDE & pushed a small bump of metal UP onto the ramp of the lobe. this motor as I said Has clearanced rods, & nothing was even close when I spun it aroung before buttoning it up! i BELIEVE THE CLOSEST ROD TO THAT LOBE IS #4, BUT IF THE ROD WAS TO HIT THE CAM, IT LOOKS LIKE IT WOULD HIT IN THE CENTER OF THE LOBE, not a glancing blow from the side towards the outer part of the lobe. hard to describe. Has anyone here ever run into such a thing ? thanks for your help.