In the March '98 issue of Super Chevy, my son Rob outlined what went into resurrecting a '73 El Camino that had been in the family since new. Teenagers can be fickle at times. Rob had wanted the 93,000-mile original Elky, then, after we got it in tiptop running order, decided he'd rather have a car with a blue oval badge. His loss, my gain.
"Smog" cars from the '70s are slugs; low horsepower, poor driveability, and miserable fuel economy. The El Camino was typical of the era, with an emasculated 145hp 350 that inhaled through a two-throat carb and dumped its exhaust out of a single 2-inch pipe and muffler. Adequate is the kindest thing I could say about its performance and, as much as I like the old beast, it wasn't much fun to drive. It definitely needed more power.
After studying what was available to pump up the trusty 350's power output while keeping it reliable and street-worthy, I found there were two major manufacturers offering complete, integrated systems. Both are highly reputable and renown for topflight engineering and quality products. Both companies' systems offer relatively comparable performance gains, and there's not a lot of difference in their pricing. Ultimately, I opted to go with one of Edelbrock's Total Power Package Systems for Chevy small-blocks.
Edelbrock has four distinct power packages for small-blocks, each a group of parts matched for a specific level of performance in a desired rpm range. One, the "Performer Power Package," is engineered for a broad, streetable powerband with more grunt from right off idle to 5,500 rpm. The other three are progressively less streetable and more oriented to high-rpm horsepower. Most of its applications are 50-state smog legal, which is important in a lot of regions. All I wanted out of the '73 Camino was more grunt for the street, so the basic Performer Power Package was my choice.
Depending on the specific year of the car and engine, there are several variations of components in the Performer Power Package. The appropriate components for the '73 start with a pair of Performer aluminum cylinder head assemblies (PN 6075). These heads are cast from 356 alloy and heat-treated to T6 specs. After the seats are given a three-angle grind, the heads are fitted with swirl-polished, one-piece 2.02-inch and 1.6-inch stainless steel intake and exhaust valves. They have excellent low-lift flow (i.e. velocity, which equals very good low- and midrange response) and at .500 lift flow 233 cfm on the intake and 172 cfm out the exhaust ports-a great balance for a high-performance street setup.
The matching camshaft kit (PN 2102) features a split pattern. Using 1.5-ratio rocker arms, intake lift is .420 and exhaust is .442. The durations for intake and exhaust, at .050, are 204 and 214 degrees, respectively. Edelbrock's "Performer Link True-Rolling" timing chain set (PN 7802) is available to ensure accurate cam timing, and is a worthy upgrade from a stock replacement part. The Performer intake manifold (PN 3701) is a dual-plane, low-rise unit designed, just like the heads, for excellent low-lift velocity to give crisp low- and midrange throttle response as well as good horsepower production through 5,500 rpm. Finally, there's the Performer Series square-bore carburetors. The recommended carb for the smog-legal Performer Power Package is a 600-cfm unit (PN 1400) with electric choke plus provisions for EGR and a fuel vapor outlet.
To maximize the gains from the package, we're going to dump the stock exhaust manifolds and single exhaust and replace them with "shorty" headers and dual pipes. According to Edelbrock's in-house tests, a stock displacement 350, with the same 8.5:1 compression ratio and the same package of parts we'll be installing, is good for 310 hp at 5,000 rpm and 378 ft-lbs of torque at 4,000 rpm.
If all goes well, in the next couple of issues we'll showing the basics of the installation, then fit the new exhaust system, get the tune dialed in, and dyno test it. Since we'd dyno'd the rig in fresh, stock form, it'll be real interesting to see how much punch will be added to the formerly limp-wristed small-block, and what the Performer Power Package does for our old El Camino's all-around performance. Best of all, there's no wild guesses about what parts are suitable to use together to get the best results.