Mr. Gasket High Performance Thermostats eliminate the huge swings in coolant pressure that plague lesser thermostats at high rpm, when coolant temperature and pressure can battle for control of the thermostat and prevent it from opening at the designated temperature. Fully compatible with GMs, Fords, and AMCs, they open at 180 degrees every time, regardless of engine rpm, and their high-flow design and brass and copper construction eliminate the damaging effects of cycling when you're stuck in stop-and-go traffic. Eliminates the huge swings in coolant pressure that plague lesser thermostats at high RPM Fully compatible with GMs Fords and AMCs Opens at 180 degrees regardless of engine rpm High flow design with brass and copper construction Eliminates the damaging effects of cycling when youre stuck in stop and go traffic