The '79 Chevy Big 10 we threw together at the last minute to run cross-country in Rod & Custom magazine's 2007 edition of Americruise has proven to be an excellent platform for a long-term test truck. As this is being written it is early September and the '79 has already logged an additional 3,000 miles on top of the 5,200 miles we clocked last June while attending Americruise.
As those of you who are familiar with the Chevy's initial buildup can attest to, there were several mechanical areas that had to be skimmed over in order to be ready in time to leave. When initially evaluating the truck's electrical system, it looked to be in pretty good condition. The battery was relatively new, and the alternator was reported to have been replaced right before we got the truck. Of course, a visual inspection is only the first half of a good checkup; we hooked up a voltage meter to the battery at rest and it was storing 12.8 volts, a shade over the desired optimum reading of 12.5 volts. The next test was to verify the reading given on the stock Chevy voltage gauge was correct, and sure enough, the cutoff of our rebuilt alternator with an integral voltage regulator was right at 14.9 volts. Thankfully, as the passing of time would prove, the charging system we left with served us well, but the odds were 50/50 at best that things would stay that way.
That said, we'll move on to why anyone would remove an alternator that was living up to its charging duties to replace it with another one such as the PowerStar alternator from the folks at Painless Performance in Fort Worth, Texas. In the case of our '79 Chevy Big 10, the main reason was to take advantage of the PowerStar's ability to deliver high amps at low revolutions. To cite an example, the Painless PowerStar delivers a whopping 70 amps at only 700 rpm, which in the case of our '79 Chevy is right around idle with the air conditioning on in gear while stopped at a light.
Before we installed the Painless PowerStar, idling at a light with the air conditioning on meant our A/C fan's blower speed would drop as well as the cold-air output. In a heat-sink fishbowl like our late-model C-10 with factory air, it wasn't long before the stock A/C's diminished output at idle translated into a sweat-induced state of discomfort.
After installing the Painless PowerStar, our theory was confirmed: The higher amperage at idle would maintain the A/C while the truck was sitting at a light, crawling through traffic, or cruising at a truck run.
In addition to offering an immediate cure to our A/C problems, we chose to install the PowerStar alternator in anticipation of installing the Clarion sound system also covered in this issue, as well as ensuring the onboard HGM computer for our 4L60E GearStar automatic transmission wouldn't suffer a failure due to an inadequate supply of current.
See, isn't it funny-we didn't even realize all the added demands our customized C-10 makes on the charging system until we started thinking about it. Installing Painless Performance's PowerStar alternator was a pretty simple procedure that didn't take more than a couple of hours to complete. As with any specialized electrical component, there are some special precautions you should take during installation, but don't worry, we've got you covered in the following photos and captions.
The '79 came to us with a...
The '79 came to us with a basic discount auto parts-type rebuilt alternator complete with Chinese-made bearings and a plastic replacement cooling fan. Before we installed the Painless Performance low-rpm, hi-amp alternator, there was excessive noise reverberating from what we believed to be either the rebuilt alternator or the smog pump.
The first step was to disconnect...
The first step was to disconnect the ground cable at the battery. In this photo the opposite end of the ground cable is also being disconnected, but doing this alone will leave a secondary ground wire, and the 12-volt positive cable will still be hot.