Limiting the amount of coolant flow leaving the engine lets you control the amount of heat absorbed by the coolant itself. You can adjust the flow with one of these water outlet restrictor kits. They include include three round aluminum plates with 5/8 in., 3/4 in., and 1 in. I.D. holes. Simply mount the appropriate plate under the water outlet on the intake manifold. An easy and economical temperature control solution!