Jim Smart
March 9, 2011

Cooling System

Cooling systems are another area we tend to fudge on, mainly due to expense. High-quality radiators and related components are expensive yet vital to engine survival and longevity. Power comes from BTUs (British Thermal Units). The more power your Mustang's engine makes, the more crucial adequate cooling becomes.

Start your cooling system regiment with a good radiator. A clean, right-sized radiator removes excess heat and helps maintain proper operating temperature. You don't have to have a high-end aluminum radiator to get the job done unless you're making 400 hp or more. A quality three- or four-row copper/brass radiator will do the job well depending on engine power and other demands like air conditioning. However, it takes more than a good radiator because this is a team effort. You need the right fan for your application along with a fan shroud to improve air velocity through your radiator.

An electric cooling fan is an excellent option if you're building a restomod because it is reliable and effective. Just make sure you have enough fan (cfm) to get the job done. The main concern is to order the right capacity for your application. You can order too little fan capacity (CFM) and wind up with overheating. We're not convinced you could ever order too much capacity.


Transmission and axle selection depends on how much power you're going to make coupled with the type of driving you intend to do. If old-fashioned hot rodding is what you want, a Ford Top Loader four-speed or three-speed automatic will get the job done. Reliving the good old days isn't always about fuel economy or reducing wear and tear, but instead about the nostalgic experience. There's nothing quite like the whine of first gear in an old four-speed to get your motor running.

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If you want a road-going cruiser for long distance driving, you probably want to take advantage of overdrive with a Tremec World Class T-5. If you're planning 400-500 hp, think about a TKO version to stand up to that kind of power.

If you're thinking automatic transmission, you have three basic choices-Ford's C4, C6, or AOD/AODE. The C4 offers reliability and less weight for those with sixes and small-block V-8s. A small-block C6 offers durability, but with a weight penalty and more rotating mass to whirl around inside. Although there's also the FMX three-speed automatic, it's not recommended unless your Mustang came with it and you're sticking to originality. The C6 is your only choice for a three-speed automatic if you have a big-block. You would choose the AOD or AODE for the same reasons you'd choose a five-speed-overdrive. The AOD has mechanical modulation where the AODE/4R70W is electronic control.

Driveshaft selection depends upon the amount of power you're considering. Although we can offer a lot of pointers on driveshaft selection, you're better off consulting with Inland Empire Driveline Service for the best choice. There are three basic choices depending upon budget and power-steel, aluminum, or composite.

Whenever horsepower and torque rise above 250, you're going to want Ford's tough 9-inch rear axle. How you configure the 9-inch depends on the kind of power you're going to build. For horsepower and torque numbers between 250 and 300, a standard 9-inch Limited-Slip or Traction-Lok with 28-spline axles is plenty. When power goes above 300, you need 31-spline axles. When numbers begin courting the 450-500-horse mark, choose 35-spline axles along with larger bearings.

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Size Formula

Here's a basic formula to use for determining proper carburetor and fuel line sizing. Remember-sizing should go higher as expected performance and combination of engine parts (heads, camshaft, intake manifold, compression) increases. This table is based on stock or mild restomod condition. Carburetor jetting is based on where you live and the level of performance expected. As always, do a spark plug reading.

One more thing-what about fuel pump capacity in gallons per hour (GPH)? Visit www.holley.com for accurate information about fuel pump sizing for your application. What you're concerned with most is fuel demand at wide-open throttle. When fuel demand goes up, consider the use of a fuel pressure regulator between the fuel pump and carburetor.

DisplacementSuggested Carburetor Size RangeSuggested Fuel Line Size From Tank To Carburetor
250-300 ci480-600 cfm5/16 inch
300-350 ci600-650 cfm5/16 or 3/8 inch
350-400 ci650-750 cfm3/8 inch
400-500 ci750-950 cfm3/8 inch or 1/2 inch