Although adequate fuel delivery can often be obtained by installing either a large electric fuel pump or a high-volume mechanical unit, we'll actually be doing both. Installing a Holley electric fuel pump at the rear of the car, near the tank, will provide a constant stream of pressurized fuel to the high-volume Holley engine-driven pump we're also installing, thereby allowing the latter to do its job of sending pressurized fuel to the carburetor. Though this dual-pump method is slightly more costly than simply upgrading one unit, the redundant pumps will provide the best possible fuel delivery while also making the car more reliable. If one pump happens to fail, the car can still be driven on the other one, rather than leaving us stranded.

Question: It seems like there are a lot of conflicting opinions on when to change the oil in a Corvette. I've been changing the oil in my '09 convertible every 3,000 miles; is this too often? Should I just follow the car computer? Do I need to change the filter on every oil change?
David
Via the Internet

If you've been following our C4 project from the outset, you know that the past few years have seen the car make depressingly little progress toward its goal of achieving quarter-mile parity with its late-model kin. There are a number of reasons for this, not least a self-imposed mandate to minimize our theoretical cash outlay along the way. The results of our ministrations have therefore been decidedly mixed, with some highly touted "upgrades" performing well below expectations and other, oft-overlooked tweaks proving surprisingly effective.

What was the first modification you made to your late-model Corvette? If you said, "a cold-air intake," you're not alone. Cold-air intakes (CAI) offer a simple, affordable means of improving your Vette's output by increasing the amount of cool, dense air flowing into the engine. And unlike permanent changes to the motor itself, a CAI shouldn't affect your factory warranty, and it can easily be removed if you decide to sell the car.

Part 1
When introduced in 1997, the diminutive 346ci LS1 was the proverbial tip of the displacement iceberg. GM has since taken the LS1 architecture and developed a whole host of block and head designs for both assembly-line and aftermarket uses. For enthusiasts looking for max performance, the cast-iron LSX block can achieve more than 500 cubes in its tall-deck configuration.

There are certain things in life we just take for granted, like the sun coming up in the morning, airlines losing our luggage, and a Corvette that will start when we turn the key.

Just a few short years after Chevy introduced the original 265 small-block, the company followed up by offering a true legend in the form of the fuel-injected 283. Often touted as the first mass-produced motor to offer 1 horsepower per cubic inch, the fuelie 283 started a small-block Chevy performance trend that would continue for decades. The 283hp 283 of 1957 was eventually replaced with Chevy's new wonder motor, the 327. Compared with the 283, the 327 offered an increase in both bore (from 3.875 to 4.00 inches) and stroke (from 3.00 to 3.25 inches). Continuing the performance trend started a few years earlier, Chevy topped the hot 327 with the latest version of its mechanical FI setup. The pinnacle of this combination was the famous L84 fuelie motor that offered no fewer than 375 hp in 1964 and 1965.

Because of their design-and specifically the slanted orientation of the radiator-Corvettes have always borne the unfortunate stigma of running warm or even overheating on hot days. While the angled radiator is not ideally designed for maximum cooling, like much of the Corvette it is a compromise between optimal performance and aerodynamic efficiency. In reality, engineers at GM spent considerable time designing the Vette's cooling system, and given the space constraints of the engine, they did a commendable job. Indeed, most Corvette engines will be adequately cooled with the stock cooling system. Add a hot engine or compromise the cooling system's design, however, and you're sure to notice your car's temperature gauge climbing toward the red end of the scale.

Question:I'll be going overseas for about a year, and I want to know what procedure you recommend for storing my two '90 Corvettes during that time. I have a two-car attached garage, and my son will be by once a week to check on the house. If necessary, he can perform some simple maintenance while I'm away.
Bob
Via the Internet

In our last issue, we detailed the job of installing a Zip Products HD Dana 36 differential in our '96 C4 coupe. Although the installation itself went off without a hitch, all that loosening and retightening of suspension components exacerbated what previously had been only a minor problem with the Vette's rear ride height. Indeed, no matter how hard we cranked down on the stock spring bolts, the freshly modified car persisted in evincing the kind of arse-in-the-sky stance you might expect from a '79 Camaro running a pair of Gabriel Hijackers. Not cool.

Part 2
In last month's installment, Texas Speed and Performance (TSP) used a brand-new GM L92/LS3 block as the foundation to build a high-performance 418ci stroker engine. Sunset Racecraft in Lubbock, Texas, bored the block to 4.080 inches (4.065 is stock) and stuffed it full of such heavy-duty components as a custom Eagle 4.00-inch stroker crankshaft, Eagle connecting rods, and Diamond Racing pistons. TSP then completed the engine build with its own Texas Speed/Precision Race Components (PRC)-prepped cylinder heads and accessories.inline_mediumwraptextright31097697/tech/vemp_1001_high_performance_418ci_stroker_enginevemp_1001_01_o+high_performance_418ci_stroker_engine+on_the_dyno.jpgTrue

Working on an older Corvette is a bit like playing a game of mechanical Whack-a-Mole: knock out one problem, and another one immediately pops up. In the case of our '96 Polo Green coupe, we've recently spent the bulk of our time concussing critters in the differential, the better to prep the car for a planned raft of power upgrades. The solution ultimately came in the form of a heavy-duty Dana 36 diff from Zip Products, which went in with a minimum of fuss and has thus far performed beyond even our admittedly high expectations.inline_mediumwraptextrightWhile the transmission in our '96 coupe performed flawlessly at wide-open throttle, it was prone to the occasional slip or indecisive shift in everyday driving. Factor in a copious ATF leak, and it was clear that restorative measures were in order. (Photo by Kevin DiOssi)31184337/tech/vemp_1001_rebuilt_4l60e_transmissionvemp_1001_01_o+rebuilt_4l60e_transmission+1996_chevrolet_corvette.jpgTrue

I graduated from high school in 1964, at the very beginning of the muscle-car era. After being honorably discharged from the United States Navy in 1969, I purchased a '69 Pontiac GTO automatic rated at 350 hp. My best time at the dragstrip was 14.5 seconds at 101 mph, and I actually won many drag races. Today, there are V-6 family cars that would give that GTO a run for its money and still get 28 mpg on the highway. There was a time when everyone thought the '60s were the Golden Age of performance cars. I now realize that today is the pinnacle, and I am a willing participant.inline_mediuminlinewithtextright25755665/tech/vemp_1001_1994_chevy_corvette_convertiblevemp_1001_01_o+1994_chevy_corvette_convertible+full_body_view.jpgTrue

Part 1: Manufacturers A-K
Do you feel like you're spinning your wheels looking for the best suspension parts for your Corvette? If so, you're not alone. The sophisticated world of shocks, struts, springs, sway bars, bushings, and other apparatus can be difficult to navigate, especially if your goal is to pick the perfect underpinnings without breaking the bank.

Clutch Materials
Up until now, we've looked at the car and the way it's driven. Now, let's look at the different clutch materials and how we use the information to pick the right package.

Question:
I have a mass airflow (MAF) sensor in my '95 Corvette with a small round screen inside. I've seen aftermarket sensors without the screen, which are claimed to increase airflow and horsepower. Couldn't you accomplish the same thing by removing the screen from the original sensor? What, exactly, is the advantage of an aftermarket unit? If I modify or replace the sensor, will I need to buy a programmer for the ECU, to keep the "Check Engine" light from coming on?
No name given
Via the Internet

One of the downsides of upgrading a car incrementally is the tendency of such an approach to highlight existing weaknesses in the driveline. In the case of performance-modded fourth-generation Corvettes equipped with an automatic transmission, it's the stock rearend that usually fails first. We'll get to the reasons why in a moment, but first, a little history.

Here's an easy quiz: Which of your Corvette's pedals do you want to push all the way to the floor, and which one do you never want to touch the carpet? If you answered "accelerator" first and "brake" second, then you already understand the opposite but interrelated processes of hurling a high-powered car to speed and then safely bringing it to a stop.

Like all domestic cars of its era, the '71 Corvette is equipped with a 12-volt, negative-ground electrical system, with an alternator providing power while the car is running. While this type of system is basically safe, the electrical hardware in our Stingray was nearly 40 years old, so we decided to carefully inspect it for issues. Under the hood, we checked the wiring harnesses for bare wires or chafed insulation. We then checked the car's lights, all of which worked after replacing a couple of bulbs. Unfortunately, a previous owner had installed a pair of electric fans, and the wiring was a mess. To rectify this, we removed the fans and wiring and replaced them with the stock engine-driven fan and factory fan shroud. The worst thing we found, however, was evidence of a fire under the hood, in the area of the HVAC box. Though the damage was minor and looked to have been repaired, we checked the wiring and discovered what was likely a contributing factor in the fire. The fuse for the heat and air-conditioning had been wrapped in aluminum foil in an apparent attempt to make a shorted fan operable. While we've seen this done more than once, we still can't believe people are willing to risk their cars by bypassing the fuse, which is a safety device. We quickly removed the foil-wrapped fuse and replaced it with a fuse of the appropriate amperage rating, then moved on to find the remainder of the car's electrical system in roadworthy condition.

Question:

When you think of the words "Kinsler fuel injection," your mind probably recalls the mechanical injection setups of the 1960s and '70s--those ubiquitous isolated-runner systems with ram tubes for each cylinder. They were of the constant-flow variety and offered more-precise fuel metering and easier adjustability when compared with carburetors of the same era.

Light Headed
Racing Head Service (RHS) has designed a 24-degree, CNC-ported big-block Chevy cylinder head that features multi-angle intake and radiused exhaust-valve seats for up to 5 percent more airflow and increased horsepower. A thick deck surface allows these heads to be angle milled and provides increased rigidity to improve head-gasket retention in boosted and nitrous applications. The best features, however, are the CNC-ported intake and exhaust runners for optimal air volume, atomization, and velocity. The heads are available with either a 339cc or 376cc runner volume and a 121cc combustion chamber. For more information, visit www.racingheadservice.com.

Pypes Performance Exhaust
(800) 421-3890
www.pypesexhaust.com

Question: I have an '80 Corvette. When it rains, the carpet under the front floor mat gets soaking wet. I think the leak is coming from the windshield area. Do you have any idea what could be causing it?
Frank
Via the Internet

Let's be clear about this from the start: The project outlined in this story won't increase the top speed of your C6; nor will it improve its lateral acceleration. It won't shave half a second from its quarter-mile acceleration, and don't bother writing to ask about the impact on downforce at 120 mph.