[Mike Taylor 3601]

Alot of cams are more aggressive,but the problem is the valve springs,it is'nt high spring pressures causing problems,it is too weak of springs that stretches your chain.
When pressure is high enough,once cam is rotating it turns easily,because you have one lobe pushing and one lobe pulling,so to speak,when spring pressure is too weak,lifters won't stay on lobes and you loose the smooth rotation and puts alot more strain on the chain.
If you don't believe me adjust one rocker on high spring pressure engine and try to rotate engine,every rocker you adjust it gets easier,when all are set does'nt take very much to rotate engine,the faster it turns the easier it gets.
As example we use at least 275lbs on sbc and at least 325 on bbc rollers this is on just common bracket engines not that aggressive of lobes.

Mike Taylor 3601