Jim Smart
March 9, 2011

We see it all the time-Mustangs that aren't safe, nor road-ready, because not enough thought went into their execution. This includes V-8 conversions with wimpy six-cylinder rear axles, 500hp small-blocks with manual drum brakes and 5/16-inch fuel line, mega-horsepower rides with less than adequate steering and suspension systems, and clogged two-row core radiators that cause chronic overheating in new engines. We've also seen high-amp subwoofer sound systems, power windows, video systems, climate control, discharge headlights, and more installed in Mustangs with 45-amp Autolite alternators and Group 24 batteries where owners wonder why their lights are dim. There are also canyon-carving rocket ships with little more than lap belts for safety equipment.

How ready is your Mustang for what you're asking it to do? How safe is it? A boatload of ponies in a Mustang ill-equipped to accommodate all those horses is a good way to get maimed or killed. It also puts others at risk who share the road with you.

How do you get all of your Mustang's components on the same page so they work together like a Swiss watch? What's the best way to plan and execute your dream ride?

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Brakes & Suspension

Regardless of how much power you build into a classic Mustang, it must have braking and handling that will help you avoid trouble or get you out quickly. You want a Mustang that will take you in the direction it is steered, hold the road, and stop safely. The best accident is the one you avoid.

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Suspension and brakes must be matched to the amount of power you intend to have along with engine and driveline weight. You can have all the braking and handling in the world, yet come up short because you misjudged engine and driveline weight. Big-blocks, due to size and weight, call for a heavy-duty suspension with stiffer spring rates along with larger brakes. They also call for more cautious driving technique because you can't cheat physics. Braking and suspension choices are also determined by how you intend to drive the car. Road racers require a different approach than drag racers or cruisers.

Fuel System

You can build power into your Mustang's engine compartment. However, without adequate fuel delivery, you're wasting your engine's potential. Your engine must have adequate fuel volume in gallons per hour (GPH) and pressure pounds per square inch (PSI) to perform. This means you need a fuel system that delivers. First and foremost is fuel line size (diameter) followed by adequate fuel pressure. Most classic Mustangs prior to 1969 have 5/16-inch fuel lines designed for six-cylinder engines or small-block V-8s. However, when horsepower rises above 300, your Mustang needs a 3/8-inch line from fuel tank to carburetor. This means sending unit, body fuel lines, all hoses and filters, and fuel pump to carburetor line. If you have a 5/16-inch pathway anywhere in the fuel system, such as the tank-sending unit, you still have 5/16 inch.

Some carburetors, such as the Holley 4150/4160, have fuel filters and fittings at the carb inlet. This has the same effect as a 5/16-inch fuel line. It limits fuel flow and can cause fuel starvation at wide-open throttle.

Carburetor sizing and jetting are also important issues to consider because they have a direct bearing on performance. Popular logic says larger is better, but that's not always true. Too much carburetor along with too much jetting hinders power and pollutes the air. However, we'd rather have too much jetting than too little. A lean mixture at wide-open throttle can harm an engine. We suggest a spark plug reading after a good wide-open throttle run. If the spark plug is snow white, your jetting is too lean. Light tan is the optimum color.

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Fuel capacity also depends on demand, which is determined by fuel consumption at wide-open throttle. Holley tells us your engine is going to need 0.5 pound of fuel per horsepower every hour. A gallon of gasoline weighs six pounds. If your small-block Ford makes 350 hp at wide-open throttle, it's going to mandate 175 pounds of fuel an hour, which is 29 gallons. Use this formula to determine fuel pump needs: 350 hp x 0.5 pound = 175 pounds of fuel; 175 pounds/6 pounds = 29 gallons per hour.

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