Manufacturer's Part Number:
Summit Racing Part Number:
Calculates jet size from air density. Designed for Holley jets.
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These Longacre circular slide rules allow you to run your engine at wide-open throttle to find the best main jet. Start with large jets and work your way down while checking plugs, pistons, EGTs, etc., to get the best mixture for acceleration and top-end. When this is achieved, check your RAD (Relative Air Density) gauge reading and jet size. To check jetting next time, set the RAD guide on base line. Check the RAD gauge reading and find the jet size under this number on the RAD guide. This will allow for easy adjustments at the track to fine-tune your engine.