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Original Message
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| RE: drill vs jet sizes |
| By Gerry Proctor - 02/09/2004 2:14:03 PM; IP 207.133.188.254 |
There really is no such thing and you can't or shouldn't mess with the jet orifice by drilling it out. The jet size is a flow rating, not a drill size. The orifice is tapered and if you drill the jet, you'll upset the fuel free flow and theoretically make if flow less with a larger hole.
Holley recommeds that jetting changes be in two size jumps to effect any mixture changes. Each jump represents around a four percent fuel flow change but the jets are not that precise and the number stamped on the jet is only means that the jet flows withing a range. So if the jet that's in there now is on the high side for that flow rating (say a 73) and the jet you want to put in there is just one size larger (say a 74), it could be on the low side which substantially means you didn't change anything.
Jets are cheap. Cheap enough that for a modest investment you could have a jet board full of jets for a wide tuning range. |
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