A race motor capable of good power and durability is not only a product of the components you put into it, but also of how well it is put together. Without the correct tools, it is impossible to quantify such things as how tightly the bolts hold the rod and main caps together; how much clearance there is between the rod, main, and cam journals and the bearings; and even the engine's compression ratio. For these tasks and more you must have and be able to appropriately use the correct measurement tools. Many of these are fairly common in general automotive applications, but a few are quite specific to building race engines.

The one measurement tool that is absolutely necessary is a torque wrench. A torque wrench lets you specify exactly how much twisting force is applied to a fastener. Too little torque on a bolt does not provide enough clamping force, while too much torque can cause it to fail. Nearly every bolt inside the engine should be tightened with a torque wrench because every component in a race engine walks that thin line between ultimate performance and failure.

There are several different styles of torque wrenches, but no matter which style you choose, make sure you purchase a quality unit. Your engine's health depends upon the wrench's ability to measure torque accurately.

Other measurement tools that you should consider "must-haves" include a feeler gauge and a pair of dial calipers. A feeler gauge is useful for determining such things as ring gap, valve lash, and even crankshaft endplay. Dial calipers, either analog or digital, are much more accurate than trying to read a ruler or a tape measure. In general, all measurements must be accurate to within less than 0.001 of an inch, and this is only possible with quality measuring instruments.

The next step in engine-building accuracy is to purchase a dial bore gauge and a set of micrometers. The micrometer is extremely useful for measuring the diameter of a round surface. A dial bore gauge is useful for determining the diameter of a cylinder. A dial bore gauge can help you determine the quality of the honing job your machinist did on your cylinders or whether the connecting rods you wish to reuse after a rebuild have been damaged by detonation. Together, the micrometer and dial bore gauge are used to determine bearing clearances for your rod and main journals.

A dial indicator mounted on an adjustable stand, preferably with a magnetic base, also comes in very handy. The magnetic base allows you to position it just about anywhere on a cast-iron block, and you can use it to check such things as crankshaft and camshaft endplay, piston TDC, and even rocker arm movement, among other things. A dial indicator accurate to within 0.001 of an inch can be had relatively inexpensively from most tool distributors. You can also easily measure rod bolt stretch with a dial indicator mounted on a special fixture. You can begin by doing without these tools or borrowing from a friend. By the time you begin the build for your second engine, however, you will be ready for a set of your own.

Finally, there are other measurement tools that are necessary only to race-engine builders. A perfect example is when the rulebook mandates a minimum combustion chamber size for the cylinder heads or a maximum compression ratio. To produce as much power as possible, you will need to make sure your engine pushes these limits without exceeding them. If you are just getting started you can trust your cylinder head manufacturer's chamber volume specification to calculate compression ratio, but eventually you will want to measure this yourself.

A CC test kit uses a graduated burette that measures how much liquid an area, such as a combustion chamber, will hold. This allows you to measure your combustion chamber volume so accurately that you can even account for how deeply the spark plug intrudes into the chamber. Armed with this knowledge, you can calculate your compression ratio accurately to the tenth. You can then be sure all your hard work won't get thrown out after failing inspection in the tech shed.