Tuning the secondary circuit is much like tuning the idle, part throttle and cruise circuits in the carb. While the longer tipped rods deliver more fuel sooner, experimenting with a variety of rods and hangers (at the dragstrip) is the best way to dial in want your combo wants. As you are making a couple of test passes at the strip, you can observe your top rpm and tune the secondaries for best response at that operating rpm. Without knowing how your engine is setup & your gear ratio, tire size etc. it would be guessing to say just use these rods and your done.
If you already have some used q-jets, then you already have some rod sets to build a tuning kit from.
Good Luck!!
Paul
