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mon-thurs 9-5 cst
Inlet spring shims allow micro-adjustments to pop-off pressure. Shims are installed under the inlet tension springs to change the spring install height. The change in install height will increase the spring pressure and pop-off pressure of the carburetor. Pop-Off Pressure is not a fuel pressure adjustment but does affect fuel volume primarily at low speeds. Pop-Off Pressure will also affect how easily the engine can cold start.