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Big-Block Power Tune

Getting The Most Power From Your Classic Big-Block

Steve Dulcich Nov 1, 2006
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Those Corvette enthusiasts lucky enough to own a classic big-block can maximize the enjoyment of these machines with a perfect tune. Some dyno work on this big-block-equipped '66 had it at its best.

Some enthusiasts are adamant about performing every aspect of wrenching on their own, from a ground-up restoration to the more mundane maintenance chores that surround the experience of owning a classic vehicle. While we admire such resolve, and can be considered to have such tendencies ourselves, sometime a little help can go a long way. When it is all said and done, and your prized possession is finally road-ready, it is the small details that can make all the difference in what enjoyment the driving experience will bring. A good example is a diagnostic chassis dyno test and tune session. Here, the process will identify problems with the fine-settings of the engine in ways that scarcely any of us can achieve on our own. The sophisticated dyno instrumentation will monitor and record vital engine functions, and point the direction for finessing the combination for optimal power and drivability.

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This vehicle was factory equipped with a Corvette icon: an L72 solid-lifter, four-barrel 427, rated at 425 gross flywheel horsepower. The engine was rebuilt and features all stock major components.

Such was the case with Rick Stoner's fine '66 L72. This Corvette was restored true to the original form, and no detail was spared in the complete rebuilding of this classic machine. The aim of the effort was to make it as road-worthy as a factory fresh big-block Vette rolling out of a dealership lot all of those years ago. In addition to being an avid Corvette fan and collector, Stoner is the proprietor of Westech Performance Group, one of Southern California's top dyno facilities. Naturally, a buildup would be punctuated by a complete dyno session, with an eye towards drivability, economy, throttle response, as well as the more empirical measures of outright max power output. Rick's L72 big-block had the advantage of a full dyno test session prior to the engine's installation in the car, however, massaging the final installed package on the chassis dyno definitely proved worthwhile. We followed along with the experts to see what was involved in the test and tune session to allow this big-block to flex its muscle.

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Hidden out of sight behind the factory ignition shields, items like the plug wires, distributor cap, and rotor are often neglected. Such was not the case with this big-block, which was rebuilt with all-new, high-quality ignition components.

Dyno Results
SuperFlow Chassis Dyno Tested at Westech

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A remote control panel displays data and controls the dyno's function from inside the car. In preparation for a power pull, the car is run through the gears, and then brought to full throttle in top gear, and run through the test rpm range.

My Corvette
We had a chance to talk to Rick Stoner about this particular machine to gain some insight into this car and Rick's enthusiasm for the marquee. As Rick says, "It's a ground-up restoration that's been done for a little while; we went through every nut and bolt. I wanted to bring it up to a high-quality Corvette; I'm not into the national Corvette show-car stuff, but wanted a nice car and an all-numbers matching car. I wanted it to use all stock stuff, to make it the way it was when it was brand-new."

We inquired about where Rick's interest in these midyear Corvettes originated. Rick says, "I've always liked the Corvettes. I bought my first one in 1969 from a friend of mine that was going into the service. I bought it for $3,000, and I still have that car. If you can find good buys on these cars, you won't lose with these cars. I have nine of them now. It may be a big investment in these things, but I can go out and touch them, feel them, and drive them."

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With the new plugs, air filter, and basic tune-up parts in place, the first full power tests were run. Grunting against the rollers, we found a baseline of 290 hp at 5,000 rpm, and a torque peak of 331 lb-ft at 3,900 rpm.

We inquired about the engine, and Rick informed us, "The engine is absolutely rebuilt from the ground up with all stock components. I didn't put [hardened] seats [in the heads] in this one, so it will have to run leaded gas or additives if you were to drive it very much. The latest one I did, I installed the hardened valve seats so I could run unleaded pump gas with no additives. I did knock some compression out of it when I rebuilt it, but I didn't change anything else."

Rick conveyed that these cars provide a unique driving experience, "For a guy who grew up with those cars, driving them just makes you feel like you are 18 years old again. I've always loved those old cars, and the value has always been good. I like the earlier cars the best, the midyears, and the old straight axle cars. I didn't particularly care for the Corvettes after 1967. It's surprising how well these cars still perform on the road. My little '64 roadster gets 21-22 mpg on the highway with a 300hp, single four-barrel engine. The 427 car has a lot of punch to it, but I'm not drag racing them anymore, so I'm not out flat-footing, seeing how fast it will go. I'm a little too old, and if I wanted to do that I would get a race car. This is just a cruiser, something to have fun with on a Sunday afternoon, or go to a car show in, or just go for a nice evening ride if I want to. It's relaxing, it's fun, it's enjoyable, and people, when they see it, appreciate the car as well."



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