You can adjust them so that the butterfly never closes.. but its usually easier to simply take the butterfly off. Rebuild kits have a replacement butterfly if you get the right one. My 2.5 ton GMC never gets that fast.. but properly adjusted it will choke the engine to prevent going over the RPM set point... pretty amazing gadget.. easy to test in neutral... give it gas and you should hear the RPMs increase until they level out no matter how far you press the gas peddle.