I was having trouble getting my Strombergs set.  There is a small hole in the primary arm for the set screw to hit the small hole in the brass rod that controls fuel flow in the primary carburetor.  The problem I'm having is that if I use that setting, my primary arm doesn't sit at 45 degrees.  It sits almost horizontal which causes all the linkage including the throttle to bind on one another.  If I ensure the primary arm is at 45 degrees, there is no problem with any linkage.  So my question is, should I drill a small hole in the primary arm to insert a small cotter pin to ensure the set screw doesn't slide, resulting in no throttle at all ?  I tightened the set screw as much as I dare but without a hole to go into, I don't feel it it reliable.