High Performance Gear Drives

A timing set in a gear drive application contains a mesh of three or four gears. This eliminates a chain or belt. Chains and belts can stretch over time as well as "jump time" during backfires or adverse engine conditions while gear drives are less prone to skipping, which can result in engine damage and requires removal and reinstallation to correct.

One of the benefits of installing a gear drive is the "whirring" or "whining" sound that it creates from the mesh between the gears. This sound is similar to that generated by a supercharger. There are "quieter" and "noisier" types of gear drives available that are cut differently, giving you more than one option to choose from depending on your preference for sound level. The gear drive noise is primarily heard at idle, part-throttle, and when decelerating. Exhaust noise overcomes the gear-whine sound during wide-open throttle in most applications using a high performance exhaust system.

A gear drive system is a timing set in an automotive engine that uses a single or dual spur gear idler to connect the camshaft to the crankshaft gear instead of a timing chain or belt found on many engines. The gear drive timing set is enclosed by the front timing cover the same as a chain or belt drive. One of the biggest advantages of gear drives is that they eliminate any slack that would be present with other timing sets, such as a chain or belt drive. However, gear drives are not recommended for use over 7,000 RPMs or on computer-controlled vehicles that use knock sensors.

The answer to this question can vary greatly depending on the source of information. Many automotive enthusiasts will cite that chain drives are more efficient than timing gear drives because the gears cause more friction and create more noise. Research and testing has shown that horsepower on engines with either a timing chain, gear drive, or belt drive all fell within one to two horsepower of each other. These results show that if properly installed, gear drives are very close in efficiency to chain and belt drives.

Depending on the brand and type of gear drive mechanism, the installation instructions will vary. In general, the SBC engine installation is fairly simple and begins with confirming the engine is at TDC (top dead center). The crank and cam gear are then installed with the timing mark of the cam gear at the 6 o'clock position and the crank gear at the 12 o'clock position. For dual gear idler setups, the idler must be installed so that the larger gear is on the right/passenger side of the engine. The idler then needs to be checked for clearance against the inside of the timing cover and adjustments made if necessary. The gear mesh also needs to be checked for proper clearance, again with changes made if needed. Once these checks are completed, the timing cover can be installed along with the rest of the engine components to complete installation.