What better way to enjoy a waning summer evening than by jumping into your vintage Pontiac and heading to a local cruise-in for a few cold beverages and a burger off the grill? If that sounds like fun, imagine you're in the driver seat for a moment.
After tapping the accelerator pedal to inject a few shots of fuel into the Quadrajet, you hit the key, the Delco starter churns mercilessly, and the Pontiac V-8 roars to life, emitting an authoritative exhaust bark through its tubular headers. Once underway, your finely tuned engine purrs right along at highway speeds without a hiccup. Life as a hobbyist just couldn't be any better!
Upon arrival, you park your Pontiac amongst your friends and spend the next couple of hours socializing. Your honey-do list prevents you from staying any longer, however, so you slide behind the steering wheel and give the ignition key a twist, fully expecting anyone within earshot to take notice of the exhaust cackle. Instead of cranking the engine, however, the starter motor protests with a defiant click.
Most hobbyists can relate to this "hot-start" scenario-or one similar to it. It's often remedied by installing a remote-mounted solenoid relay or high-amp battery with oversized cables, and while such action might alleviate some hot-start issues, the real solution oftentimes requires replacing the original Delco starter. Even a new stock-replacement can't prevent hot-starts indefinitely, however.
Delco-Remy produced a number...
Delco-Remy produced a number of different shift-lever starters for General Motors' applications, and this cross-sectional diagram of a typical shift-lever type starter is a common sight in virtually any Pontiac V-8 Service Manual. Notice the positions of the electric solenoid and motor, and the shift-lever connecting the two. The armature and pinion gear share a common main-shaft and subsequently spin at a 1:1 ratio.
Starter Motor Basics
A typical vehicle's cranking system is comprised of a 12-volt battery, keyed ignition switch, series of associated wiring, and a starter motor. Two types of starters are commonly found on most passenger vehicles today-shift-lever and gear-reduction. Vintage Pontiac applications were originally equipped with a shift-lever-type, while modern Pontiacs feature a gear-reduction unit.
A shift-lever starter typically consists of a large, cast-iron housing containing an electric motor with an electric solenoid attached to it. The electric motor's main-shaft has an armature on one end and a pinion gear mated to a spring-loaded overrun-clutch on the other. These two ends rotate at the same speed, or a 1:1 ratio, which is commonly referred to as direct drive. The overrun clutch is connected to the electric solenoid via a pivoting shift-lever. As the electric motor spins during cranking conditions, the solenoid plunger retracts, forcing the pinion gear rearward where it meshes with the flywheel ring gear, rotating the engine.
A gear-reduction starter motor operates using the same basic principle as a shift-lever unit. Unlike its brethren, however, its pinion gear is mounted on the opposite end of the solenoid plunger and a small, high-speed motor mounted on it transmits power via an offset gear. The result is a compact unit that's more efficient, weighs less, and cranks the engine at a higher speed with more torque than a typical shift-lever type starter.
The cranking system must operate to its full capacity to carry the electrical demands placed upon it when attempting to crank an engine in extreme hot or cold temperatures, and the starter seemingly lives in the harshest environment. It's typically positioned between the engine block and exhaust system and is regularly exposed to normal underbody grime, precipitation kicked up from the road surface, and engine and exhaust heat.
Continual airflow from the engine's cooling fan and the vehicle's speed during normal operation has a cooling effect on the starter. Upon shutdown, the block and exhaust pipes continue radiating heat and the starter tends to absorb it due to its relative position, increasing its internal temperature. This can cause the starter's internal wire windings to expand and drag during cranking.
 Tubular headers are a common...  Tubular headers are a common performance modification and the tubing typically runs very close to or surrounds the starter. This often prevents the removal of a larger starter, such as the original Delco unit, without loosening the header. It also continuously exposes the starter to extreme heat, which can shorten a typical Delco unit's life. |  Hi-Torque IMI Performance...  Hi-Torque IMI Performance Products (IMI) in Whittier, California, modifies modern OEM Denso gear-reduction starters for use in vintage applications. Higher cranking speed with greater torque multiplication and the compact design make such units a popular choice when replacing a Delco starter, especially on modified vehicles with headers. This particular model (No. IMI-108N) fits Pontiac V-8s and features an output rating of 1.4 Kw. |  This cross-sectional diagram...  This cross-sectional diagram of a typical gear-reduction starter shows how they operate. Notice that the electric solenoid and motor's positions are reversed and that power from the electric motor is transmitted to the flywheel through a reduction gear set. The unit emits a characteristic high-pitch whine during cranking conditions. |