Start with a cold engine and disconnect the battery negative lead. Remove the mass air sensor and air-inlet tube between the throttle body and air cleaner by loosening the worm-gear clamps at each end. Remove the throttle cable from under the throttle-body. The cable snaps onto a ball mount, and it can be carefully pried off with a wide-blade screwdriver. Remove the connections for the throttle position sensor (TPS) and idle solenoid. The plastic connectors snap apart and will plug back in later. Dont worry about removing the TPS. A new one is included and mounted on the new throttle body.
Loosen the hose clamps that hold the two coolant hoses to the EGR plate and remove them. Here, the PCV hose has already been removed. Its a press-fit installation; you might need to use a small screwdriver to separate it from the throttle body.
Loosen the four nuts that hold the throttle body and EGR plate to the intake. New gaskets are included with the BBK pieces, so saving the old ones isnt necessary.
Remove the bracket that holds the throttle cable and TPS plug in place. Separate the TPS plug from the bracket so the throttle body can be removed.
Both the throttle body and the EGR plate can be removed from the engine at the same time. In the foreground is the idle solenoid unit, which is unbolted from the throttle body by removing the two mounting bolts. Again the BBK parts include the gaskets for installing the solenoid on the new throttle body. At the back of the EGR plate is the EGR valve that is removed by unbolting the two nuts that hold it in place and disconnecting the vacuum line from the valve. Re-install the valve on the new EGR plate using the supplied new gaskets.
The stock 60mm throttle body and EGR plate are on the right with the idle solenoid still on the throttle body (top). The BBK components on the left include a new TPS, which is on the left side of the throttle body. Note the ball stud on the bottom of the throttle body where the throttle cable attaches to the throttle plate.
While not absolutely necessary, its a good idea to trim the inlet port if youre using a stock 5.0L Ford intake. The bigger throttle-body is worth at least 10 hp, and eliminating the ledge that the bigger EGR plate creates will only make the horsepower improvement better. Start by sliding the new EGR plate on the intake and marking the manifold material to be trimmed with an indelible-ink pen. Mark 360 degrees around so you know how much to cut.
Cover the engine with an old blanket or sheet to keep the shavings from getting all over the engine bay. Also, stuff a clean shop rag into the intake port so the shavings dont get inside the engine. Use a grinder bit with an electric drill, compressed-air tool, or Dremel tool to trim the stock intake. You only need to go about as far as the shiny part thats already trimmed down here. Dont enlarge the whole port, but try to create a sort of ramp or tapered area for the air to exit the throttle body and enter the intake. The main goal is to eliminate a hard edge the air has to travel over to get into the intake, since the stock intake port is smaller than 70 mm in diameter.
Check to see how much youve cut away by re-installing the EGR plate on the intake. Feel inside with your index finger to ensure that the ledge is smoothed out. When finished, use a suitable vacuum cleaner to suck up the metal shavings from inside the port and on the blanket before you remove the blanket from the engine.
Re-installing the BBK throttle body and EGR plate is basically a reversal of the stockers removal. Both parts are held to the intake with four nuts. The idle solenoid and EGR valve bolt to the BBK throttle body and EGR plate, respectively. All the electrical connections plug back into the same places, the coolant hoses screw back onto the EGR plate, and the PCV hose slips onto the new throttle body. Once installed, the inlet tube and mass air sensor slip back into place. The air inlet tube is a tighter fit on the new throttle body, but it will fit over the new BBK unit.
Finally, the new TPS needs to be adjusted properly. After reconnecting the battery, hook the black (negative) lead of a digital voltmeter to the batterys negative terminal. Pull back the black insulation that covers the three TPS wires, and cut away just enough of the green wires insulation to allow the voltmeters red (positive) lead to touch the wire inside. With the ignition on (the key in the on position, engine not running) and the meter set on the 20-volt scale, it should read between 0.8 and 1.0 volt. If not, loosen the two screws on top of the black cover (arrow) of the TPS and ever-so-slightly rotate the housing so the meter reads about 0.9 volt. Retighten the screws after the adjustment is complete.
The finished installation should look like this. The performance improvement is real and noticeable. As installed on this 90 Mustang, we could feel a difference on the freeway with the car cruising in Fifth gear. When tipping into the throttle at about 60 mph and 1,800 rpm, the engine pulled harder, and in some situations, the bigger throttle body eliminates the need to downshift to a lower gear.
For ages, the first thing most people did (and still do) to get more power from a two-barrel carbureted engine was upgrade to a four-barrel carburetor and a better intake manifold. For modern-day 5.0L Ford EFI engines, increasing induction airflow relies on a similar theoryexcept now the upgrade is to a bigger throttle body.
In the old days, you had to buy the carb and intake at the same time. But today, theres an added benefit. A BBK throttle body and EGR plate will fit on a stock 5.0L intake if you dont have the dough to buy the TB and intake at the same time. You can buy a BBK unit like the 70mm one here, then later procure one of many intakes (such as from Edelbrock or Ford Motorsport SVO) available on the market today.
BBKs throttle-bodies for 5.0L small-block Fords includes 65mm, 70mm, and 75mm sizes to replace the 8793 60mm stocker (58 mm on 86 engines) found on Mustangs. BBK says the 70mm is a good overall size for most street-car applications that allows you to grow when you upgrade to additional engine mods later on.
If a big cam, better heads, and maybe even a supercharger are in the future, then a 75mm throttle body would be a better bet. BBK also has an 80mm unit for more radical street/strip setups. The 70mm unit shown being installed here offers a significant 36 percent increase in throttle plate area over the stock 60mm. Of course, upgrades like this are not just limited to Mustangs. The BBK unit will also fit in other Fords with 5.0L EFI small-blocks such as Thunderbirds, trucks, and even Lincoln Mark VII LSCs.