7. Water Flow Rate Regulation
The speed that the coolant flows through the engine and radiator is critical to how many BTU's of heat is absorbed and then removed. A flow that is too slow might cause a high retention of heat just as a flow that is too high might not allow proper removal of heat by the radiator.

Sizing the water pump pulley is one way to control the flow rate of the coolant. Passenger car pulleys are designed to flow efficiently in the lower rpm ranges that those cars experience. For racing applications where our engine speeds are greater, we need to use a larger-diameter pulley on the pump to reduce the rpm of the pump to flow the coolant slower.

Reducers can be installed under the outlet where the radiator hose connects to the engine to regulate the flow rate of the coolant. If your coolant temperature is either too cold or too hot, these simple and cheap discs with various-sized holes could help tune your coolant temperatures.

8. Fuel Line and Filter
The fuel lines and filter are low-cost items that should be replaced maybe twice a year. The use of pump fuel can soften the glue that holds the filter element in place and allow the fuel to bypass the element meaning trash and debris could make its way to the carburetor.

When using mechanical engine mounted fuel pumps, the fuel line is in suction. An older weak line could partially collapse and cause fuel starvation problems. The engine will run rough or die and while we are frantically searching for an electrical or other problem, the fuel lines typically go unnoticed.

9. Full Throttle Check
Periodically check that your throttle is going full open when the gas pedal is fully extended. Always use a throttle stop under the pedal to prevent bending the throttle linkage or the carburetor throttle shaft.

The ratio between the pedal motion and the degree of rotation of the throttle shaft needs to be correct to prevent the quick off-to-very-on syndrome. One of the driver aids is developing proper throttle control and that is very hard to do if there is little travel distance for the pedal. The pedal needs to travel from 21/2 to 3 inches at the ball of the foot.

10. Partial Throttle Testing
This is an advanced technique that some upper level engine builders perform. It's running the engine on the dyno using partial throttle all of the way up through the rpm range. The fuel mixture patterns can be much different with some carburetors when the throttle is only halfway open.

The reality is that many drivers only are able to use partial throttle due to lack of adequate traction on slick track surfaces. Many dirt races are won with the driver never using more than half throttle. So, how does your engine work under partial throttle conditions?

Next time you turn your motor over to the engine builder for dyno testing, ask him to run a partial throttle test. If he asks what that is, inform him. This simple test could help you discover fuel mixture problems before they cause a meltdown.