You bought this car with a "For Sale As Is" sign in the window, and that is the way you're going to sell it. This car only came with a V-6 engine. I can't imagine how anyone shoe-horned a V-8 into it, but there are way too many problems to list that you're going to run into. First let me start with the slightly less-obvious ones. Knowing these might make you throw in the towel before you waste a lot of money and frustration on a project that can't work.
A 350 with a carburetor or throttle body injection requires very low fuel pressure. Carburetors will be overloaded with much more than three or four pounds. Throttle body injectors run at around 14 psi. Multi-point systems like this car came with run in the area of 45 to 55 psi. That would cause a fuel / air ratio much too rich for any Engine Computer to compensate for.
The front coil springs are designed to hold up the weight of the front of the car with a V-6 engine. GM and Ford V-8 engines are 100 pounds heavier than the comparable Chrysler V-8, and those are a couple hundred pounds heavier than a V-6 engine. The first problem is front ride height is going to be too low, and new springs won't fix that. Every shop has a small book that lists every car model and year, where to take those measurements, and what they should be. Those are published specifications that have legal ramifications. Your handling and steering response will feel like you're driving a delivery truck.
Every manufacturer spends thousands of hours for research and development just for the brake system on each new car model. The goal is to have a balanced braking system, front-to-rear, under normal driving conditions. Part of that system is the carefully-selected proportioning valve for the rear brakes. Those limit rear brake fluid pressure under hard stops to reduce rear-wheel lock-up. That valve lives inside the combination valve, and those will have different valving and spring pressures based on such things as with or without air conditioning, with or without rear heaters, and number of things on a list of optional equipment. By adding three hundred pounds to the front of the car, you never gave any thought to cobbling the combination valve to try to get back that balanced braking. With more weight, you'll need to push harder on the brake pedal, and with the added weight transfer to the front, you'll have real easy rear-wheel lock-up. Skidding tires have no traction and can result in the rear trying to pass the front of the car. That is the sole reason we came up with early versions of rear-wheel-anti-lock brakes for pickup trucks. To stop the rear tires from skidding on your car, you'll need to reduce brake pedal pressure, but that also lowers stopping power at the front tires. There's no way around it; you will have seriously-increased stopping distances, and that can come back to bite you if the other guy runs a red light and crashes into you. His lawyer or insurance investigator will convince a jury that you were partly at fault for the crash because you were less able to avoid it, and they will be right. Insurance adjusters love to find lowered cars, raised trucks, and any other modifications, as long as it is not on their client's vehicle.
The front brake calipers are sized to provide the necessary stopping power based on the car's weight. Stopping a car with added weight will overheat the brake pads much easier than normal, and that will result in one form of brake fade. That doesn't always occur suddenly from one stop to the next. It is more likely to come in gradually, and make you need to push harder and harder on the brake pedal, often too little to notice until it gets real bad. Each time you have to push harder to stop, the additional heat build-up occurs faster and faster until you sail through an intersection without stopping.
The more-obvious problem comes from all the computers the insane engineers have hung on their cars. As late as 1999, a Cadillac could have as many as 47 computers, and that gets much worse every year. Those all talk back and forth to each other over a pair of wires called the "data buss". The Transmission Computer needs to know road speed, throttle position, coolant temperature, and engine speed to know when to initiate a shift. It gets that information from the Engine Computer. Both of those share data with one of the most complicated computers on the car, the instrument cluster. That receives only digital information from all the other computers to turn warning lights on and off, and to run the gauges. If you need to eliminate the high-pressure fuel pump in the gas tank, it is part of an assembly that houses the fuel level sending unit. You don't want to drive around with the "Low Fuel" warning light always on. The fuel level sensor is an input to the Traveler Computer that shows the "distance to empty". If that shows anything, it is not going to be close to accurate.
The Body Computer is the main one that wakes up all the other computers. In return, it expects to get a verification signal that they did indeed turn on. No Engine Computer can run a carbureted engine, and a V-6 multi-point computer is as different from a V-8 throttle body computer as Chrysler's 1977 Lean Burn Computer is from the navigation computer on NASA's lunar lander. Even if you tried to leave the original computer on the car, it will detect that it isn't connected to injectors. Those will trigger six diagnostic fault codes. There are well over 2,000 other things the Engine Computer can detect, and when set, the majority of those codes stop other computers from running some of their self tests. Most of the other computers detect problems and set related fault codes to indicate their circuits or systems that need further diagnosis. You're going to be swimming in hundreds of fault codes, then, when a problem does occur, you won't have any idea where to start looking. That is the whole reason they had to design in those fault codes. Without them, it could take weeks to track down and diagnose a running problem with a simple cause.
The air bag system is another problem. The crash sensors need a specific rate of deceleration to detect a crash. With a lot of additional weight, the car is going to decelerate slower, possibly to the point the air bags do not deploy when needed. GM is going to love this because the modifications will completely absolve them of any liability. There are dozens of class-action lawsuits every year, many involving injuries. You can say goodbye to any involvement with those.
I built a few cars many years ago. One was a '73 Dodge Challenger with the engine moved back 16 inches for better weight transfer when racing. The transplanted engine was the same shape and weight as the original one, the front torsion bars were easily adjustable for the reduced front weight, and that car was used strictly for racing on race tracks. It launched really great, but with all the other problems, I ran it four nights and gave up. I figured out it was impossible to improve on what the engineers spend their entire careers designing. My project cars had no computers, and they were meant to go fast on a paved oval. No lawsuits, no layers, and not much concern for comfort. Looking back on those, I wish someone had warned me then the way I'm warning you now. You need to look at this as an opportunity to go out and find exactly what you want, and buy it.
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Monday, April 1st, 2019 AT 7:52 PM
