[Bruce Lancaster]

A common Mallory problem is advance starting late and moving slowly. First easy test can be done even without more than the single timing mark on an 8BA...with a timing light on that slowly open the throttle by hand. Advance should begin to move just a little bit above idle and keep moving rapidly from there as you speed up engine. If advance isn't early and rapid, you will have hesitation.
On richness, test with air cleaners off. MANY multi carb air cleaners are VERY restrictive. Note also that late timing gives some of the same symptoms as richness...