How to put a 70mm throttle body on your 4.6L.
Written by Mustangworld.
Lots of pics, I hope your on the net at 28.8 or faster.
We bought a larger 70mm throttle body to replace the stock 65mm unit. It was a 70mm Throttle Body from BBK. Why didn't we get the 75mm ? Because we plan on keeping the stock heads and are going to be adding a supercharger. The 75mm is simply too big for the stock intake / heads. Don't get us wrong, buy a 75mm if you want to, but with the stock intake system & heads, 70mm is cool. You can look in and see the stock intake is just less than 70mm so anything larger would require a port to maximize performance. If you are running the Motorsport heads (and further porting them at that) then we'd say go for the 75mm (it's only $10 more), but for the stock intake / heads the 70mm unit will flow fine. The kit was $179.00 and included a new gasket but no new Throttle Position Sensor.
We decided to show you an install of a throttle body that does not come with a new Throttle Position Sensor (like the BBK units). It's a piece of cake to install with one exception, the removal of the stock TPS screws! If you don't want to deal with using an air impact wrench or grinding the screws, then go for a Ford Motorsport throttle body. One thing we like about the BBK units is that the manual idle set screw is easy to reach, right in front of the unit.
The installation below is similar for the COBRA throttle body, the only difference is the Cobra's dual unit throttle body design. All the cable connections, TPS settings, etc. we describe below are the same. In fact most all aftermarket throttle bodies install the same way on the 4.6L.
The 70mm unit gives you more HP at the mid to higher rpms (you can just feel it), and more HP with a blower application as well.
On the 4.6L the Idle Air Bypass and TPS settings are implemented differently from the 5.0 and installation on the 4.6L is real easy, in fact if you don't want to bother setting the manual idle, you can just close it up all the way and let the computer handle the idle control. If you are running a Mondo blower application then you can simply unplug the Idle Air Bypass connector and set your idle manually with the set screw on the throttle body. We recommend using the Idle Air Bypass (computer idle control) for daily driving and for every stang short of one being used as a "1/4 mile strip only" project stang, your idle will be much smoother with computer control. Though we also recommend setting the manual idle screw to around 500 (low) as a backup. This is also easy do to, just read below.
Below : TB - Short term for "Throttle Body". TPS - Short for "Throttle Position Sensor".
OK... HERE WE GO!
IDLE ADJUSTMENT : After you've re-connected the battery and you have just finished the TB install (all connectors plugged in). You can now set your manual idle. Start up your stang and let it warm up for a few minutes, now, in the engine compartment, while the engine is running, disconnect the Idle Air Bypass plug connector. Your stang may almost "putt out" or it may run at a higher rpm, while the Idle Air Bypass plug is disconnected, you can set your idle with the gold colored screw on the front of the TB. Set it to around 500 RPM (fairly low). Turn the screw clockwise for lower idle, and counter-clockwise to raise the idle. When your done setting the manual idle, you can re-connect the Idle Air Bypass connector and your engine will return to computer controlled idle.
STICKERS ON THE STOCK TB : The stock throttle body comes with these adhesive paper stickers on the top AND bottom, when removing the stock TB, MAKE SURE you don't let these stickers fall into the intake hose, or you will be sucking down paper ! Make sure you check for any crap that may have fallen into your intake hose during installation.
HOSES: MAKE SURE all intake hose connections are returned, this includes hose connections to the throttle body, the Idle Air Bypass AND PCV hoses.
YER DONE DEDE !
Til next time... See ya on the street !