another thing to look at is lifter preload. too much will cause the engine to idle rough. the lsa on the cam i mentioned is 111 degrees. it has 292 degrees of seat timing, 148@.200 at the lobe, 152@.200 at the valve. a solid tappet will idle better than an hydraulic. but, this engine combo does not lope, just a moderate rumble typical of lower compression engines. i did a bunch of tuning, built mucho distributors until i was happy. there is no jumping around in the engine bay.