Thread: Vac secondary test?

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Go down the road about 10-20 mph then floor it!Be safe about it though!come up to speed and,let completly off of the gas as fast as you can.When you do this you will hear a big "woosh". This will be the secondaries closing.The best way to really adjust it,is to take it to the track and pay attention to your times,and MPH.I started with a weak spring and changed springs until ,my et,mph got it best.When my mph and et started to fall after peaking,I went back to the spring I put in just before.They sell a kit of a few springs(color coated) for I think less then ten dollars.Theres also a little red book holley sells.This thing is a Holley " bible" .Theres another that has more ibfo and tricks ,but I forget the writer.There is also plenty of pics. to help get a better idea of tuning your holley.