what is the difference in the secondary springs?
i was told to use the silver springs in a tunnel ram, what are the different springs? what do the colors mean?
The Holley secondary springs regulate the opening point and rate on a vacuum secondary Holley based on venturi air velocity. When dealing with a vacuum secondary carb, keep in mind that they will not open in park or neutral. The engine must be under a load. Place a paperclip on the secondary rod horizontaly and slide it up to the base of the secondary diaphragm housing. Drive the vehicle under full load and check the position of the clip. if it is pushed down they are working. If not check the diaphragm and gaskets for damage and clean the vacuum ports. Also keep oin mind that they may not open if the carb is too large for the engine or if the spring is too stiff. To increase the secondary opening speed install a lighter spring. the common spring kit (20-13) will include 7 springs the following list is from heavy to light. Black, Brown, Plain, purple, yellow, short yellow, and white. I recommend starting with the black spring and working your way down. When you can feel the secondary come in (kick) go back to the previous spring.