By Barry Kluczyk Photography by THE AUTHOR

tructural rigidity has long been the Achilles heel of unibody cars—particularly cars from the muscle car era, such as the first- and second-generation Camaro. The issue becomes more acute with a significant jump in performance when greater horsepower and handling capability expose the functional boundaries of the body structure.

A weaker structure is not only prone to metal fatigue and even ripping in some areas, but it makes it more difficult to put all the car’s power to the pavement, whether in a straight line or in corners. It’s simply impossible to optimize launches or handling with excessive chassis flex.

So, just as long as there have been flexible unibodies, subframe connectors and other structural enhancements have been the cure—but even they have had their compromises. Typically, they’ve necessarily followed the contours of a car’s floor, which often means less-than-optimal strength. Also: Following the underside of the floorpan often reduces ground clearance while also creating somewhat of an unsightly profile.

1. Is it the real deal or an imposter? The numbers tell the story on your classic Chevy.

hen it comes to finding out your car’s factory options and features, the best place to start is the vehicle identification number (VIN) plate and the trim tag. In most cases, these two stampings will not provide every piece of information you want, but it’s easily accessible and can sometimes reveal some cool details. If you want the car’s full history, other documentation like a build sheet and Protect-O-Plate are needed, but those items are often long gone on an average Chevy from the muscle car era. Finding a build sheet hidden in the interior or on top of the gas tank is like finding buried treasure. We’ll cover some details of the build sheet, but the main purpose of this article is to explain some of the nuances of the VIN and trim tag through the years.

To simplify things, we’re narrowing the focus of this article from 1960 through 1980 because there are many variations of VIN and trim tag configurations and other documentation differences. Even in that 20-year span, there are dozens of variations, sometimes within the same year of production. Variations could depend on the factory, build date, or the combination of the two factors, especially in the case of trim tags.

We’re using a few real-world examples of cars: a ’63 Impala SS convertible, a ’64 Chevelle Malibu, a ’66 Nova, a ’69 Camaro, and a ’73 Nova. This information can help you make quick observations when looking at a car to buy, or if you’re simply curious about a car’s original configuration. There aren’t enough pages in this magazine to cover every option code or configuration, but we’ll do our best to simplify the process and give you some of the highlights from popular Chevrolet applications from the ’60s and ’70s.

By Jeff Smith Photography by The Author

he Bible says that idle hands are the devil’s workshop. Our take is a little different. When it comes to setting the idle mixture on your street-driven engine, your hands will be plenty busy adjusting, tweaking, and setting several different parameters. This may not sound like something to account for an hour or so of your time, but trust us, it’s worth the effort.

If you think about it, a street-driven engine spends much of its time running with a closed or near-closed throttle. Waiting for the engine to warm up, sitting at a stoplight, cruising down the highway, or on city streets are all conditions where the throttle is just barely open. With most carburetors, these situations require a throttle opening of roughly 10 to 15 percent. This places throttle action well within the realm of the idle circuit.

That statement may come as a bit of a surprise to many automotive enthusiasts. But if your street engine idles at roughly 12 inches of manifold vacuum or higher, then your engine probably runs down the freeway at not much more than 15 percent throttle opening, which falls within the control area of the idle circuit in your carburetor.

By Jeff Smith Photography by The Author

hile we all love our older muscle cars for their style and performance, this is especially true for this writer when it comes to first-generation Chevelles. While they have tons of flair, they do lack a bit of sophistication when it comes to things like sealing the interior. This is nowhere more evident than the suggestion of a seal between the steering column and the floorpan. I own more than a couple of A-bodies that sport a near ¼-inch gap around the steering column that allows hot underhood air, dirt, and fumes to funnel straight up the steering column at road speeds.

I’m in the midst of a complete restoration on our ’66 SS396 and I noticed a small ad in this publication for a firewall seal designed to solve this problem. JJ’s Rods is owned by Jeff Johnson. He experienced the same issue with many street rods and decided to come up with an answer for this little dilemma. This led to his E-Z Firewall Seal that he has now expanded into the muscle car market.

The E-Z Firewall Seal has won numerous street rod awards along with SEMA’s Product of the Year award in 2018 for its elegant and simple solution. With regard to the Chevelle and GM A-body market, Johnson offers a couple of different kits depending upon whether the car is equipped with an automatic or, as in our case, a floor-mounted four-speed to accommodate the manual clutch linkage. JJ’s offers a similar part specifically for early Camaros and Firebirds as well as ’69-74 Novas.

By ACP STAFF

t one time selecting a Chevrolet starter was easy enough, as there really was only one choice. However, since the late ’80s, the OEMs have steadily moved away from direct-drive starters and toward gear-reduction starters, and the aftermarket has followed suit.

Although gear-reduction starters are more complex, making them more expensive, they are also smaller, lighter, and more efficient. These starters typically achieve a gear reduction ratio of 4:1. These starters use smaller, faster motors that draw less amperage. A 4:1 gear reduction ratio also means that a gear-reduction starter can often produce more torque than a much larger, heavier, direct-drive starter. In some cases, a direct-drive starter can weigh as much as two times more than a comparable gear-reduction unit. That represents a significant power/torque to weight ratio benefit, and it also means they are physically smaller and often easier to install.

While gear-reduction starters have a variety of advantages in some cases, when originality is important, a direct-drive starter may be more desirable. Regardless of the type of starter used, when it comes to Gen I and II Chevy small-block starters there are two basic choices, and which is used depends on the diameter and tooth count of the ring gear on the flexplate or flywheel. The large ring gears are 14 inches in diameter with 168 teeth and require starters with offset mounting holes. The smaller ring gears are 123/4 inches in diameter with 153 teeth and the proper starters have two holes parallel with the back of the block.