Is adjusting the valve lash while dyno testing an effective way to see if a cam change would be warrented? I know its not exactly the same since you change lift/duration/ and opening and closing events all at the same time. However was thinking it would point in the right direction.

Yes, valve lash changes can indeed point you in another direction in regards to cam timing and/or lobe design.

 

Evaluating engine performance on the dyno with varying lash settings is an appropriate method in determining if a camshaft change is warranted.  The torque band can also be moved around with lash changes in lieu of advancing or retarding the camshaft itself.  As a general rule, if a looser intake lash increases performance, then advancing the cam or having a camshaft with a shorter duration can also do the same.  The reverse is true if a tighter lash increases performance.  Changing the exhaust lash gets more complicated in that exhaust tuning may also be required depending upon the scavenging that’s taking place.  By experimenting with loosening one lash while tightening the other, what the engine sees as the running ‘lobe center’ can also be subtly altered thus giving some interesting results.

Lorena, Texas (South of Waco)