June 2010 Chevy High Performance Letters - Performance Q & A

Tom Truty May 5, 2010 0 Comment(s)
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Now it's time to take a little search around your brother's Chevelle. Under the back seat is usually where Chevrolet put the buildsheet as the vehicle was assembled. This sheet will list all of the RPO production codes, which will let you decipher what your Chevelle was originally equipped with. If there isn't one under the rear seat, check between the fuel tank and the trunk floor. This one is a little tougher, as you will need to drop the fuel tank. If you're lucky enough to get your hands on the original buildsheet you'll need a road map to tell you what all the RPOs mean. The best reference book we know of for this is the Catalog of Chevelle, Malibu & El Camino ID Numbers 1964-87 by Cars & Parts magazine. This book is a wealth of information on all A-body Chevrolet products. It will decode your VIN, body number plate, engine number, and Protect-O-Plate. The book is distributed by Motorbooks International under catalog ID number 119465AE. You can contact Motorbooks directly and have the book drop shipped right to you. This is a must have for any Chevelle enthusiast. Good luck with your search. Source: motorbooks.com

It's A Spring Thing
Q: My '69 Camaro is about to get a 350 LT1. I have disc brakes and 2-inch drop spindles that I purchased from Performance Online. The brakes consist of 13-inch rotors with dual-piston aluminum calipers. To round out the frontend package, I also have a set of Performance tubular A-arms. I intend to put QA1 single-adjustable shocks on it. What front springs do I use, stock or 2-inch drop? It will be used for street and maybe an occasional dragstrip or autocross. Also, it will have A/C. Thanks for your help.
Scott Langston
Fort Wayne, IN

A: Which front springs you choose is completely dependent on what you wish to use your car for. You stated that you would like to drive it on the street, play on the dragstrip, and toy with autocross. All three of these disciplines take different types of springs and finding a happy medium can be a challenge.

What do you wish the ride height to be? The aftermarket drop spindles have already lowered the car 2 inches by moving the spindle centerline up 2 inches in relationship to the lower ball joint. If you also install 2-inch lowering springs, the car will be 4 inches lower than stock. The front subframe may find the pavement driving around on the street in normal driving. You need to answer this question first. Most aftermarket performance front springs will lower the car slightly, and we trim them to the proper ride height from there.

Springs are designed differently for handling versus the dragstrip. For handling you'd want to increase the spring rate of the spring to prevent body roll and load the outside tire for grip. In drag racing you aim to run the lowest spring rate possible that will support the weight of the car. A light spring-rate spring that is highly compressed will aid in the weight transfer to the rear tires on the launch. We would go for a street-handling performance spring. Check with Eaton Detroit Spring; we've used them several times to make springs for oddball applications. Eaton has the factory prints from all the domestic auto manufacturers in the muscle car years and could build you a big-block spring-rate Camaro spring that will give you a stock ride height, or build the spring at the ride height you wish based on your measurements. Give Eaton a call for more information and visit the website and bone up on Spring Tech 101. This is a very informative handbook to educate you on the finer points of spring design and selection. Source: eatonsprings.com


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