Hi guys/gals!

Camshafts are still a bit of a mystery to me.

About what duration do cams make a engine thumpy at idle/poor vaccum?

Is there a general formula/guide I can follow?
Is camshaft duration porportional to vaccum loss?

In a nutshell, what I am asking is, for a street engine how much duration is too much? Or does it come with years of engine building like you guys have?

lol i'm all questions,
thanks in advance,
-CJP