More preparation work, this time we hook up the necessary vacuum lines
and PCV to the rear of the upper intake. You will need to do a few adaptations
to fit all the lines. The most important being the EGR and Fuel regulator
vacuum lines. Also reinstall the thermostat elbow.
Now is time to start removing all the lines, throttle linkage and electrical
connections to the TB, EGR, etc. If not experienced enough with the
engine, tag all lines for future reference, or use a digital camera
or camcorder to trace all your steps.
First step is disconnecting the battery negative terminal, then remove
the passenger side spark plug wires, coil wire and distributor cap,
leaving the wires hooked to the cap, and toss them to the drivers side
of the engine bay.
Remove the thermostat to get rid of most of the coolant inside the
lower intake. This is very important to do at this time, else coolant
could get into the lifter bay under the intake and into the oil pan.
Now you can start removing the stock upper intake, complete with throttle
body, make sure all lines and connections are removed first.
Place the distributor rotor pointing to the #1 cylinder, that's around
1 o'clock. Mark the relationship of the rotor to distributor using a
marker pen. Remove the retaining bolt and lift the distributor out.
Remember NOT TO CRANK the engine !!
the fuel rails out by first removing the rails bolts, if you don't have
a fuel rail disconnect tool don't worry it is not needed. The injectors
get out easily, just pull them out of the lower intake. Get the rails
with the injectors out of the way just by moving them to the passenger
Next remove the lower intake bolts and use a pry bar to pull the lower
out, it could take some force to get it out. At this point you can see
the lifter bay, and probably some coolant got in there, get it out with
a sponge before it goes into the oil pan. If that fails i advice to
change the oil after you finish the setup. This is actually the best
thing to do since gasket leaks could also let coolant into the engine
and only an oil change can tell you this.
Once the lower is removed you will see the exposed head intake ports
and coolant passages, make sure NOTHING gets into the ports or you can
ruin a valve or worse. Use a lint free cloth to cover it.
Now it is also a good time to clean the engine valvecovers, inspect
and/or repair damaged wiring insulation, etc.
Clean and remove any gasket material left on the head intake ports,
this is very important, you want a perfect seal, else coolant and oil
could mix or you could get vacuum leaks.
Next is time to install the cobra lower intake, install the intake
to head gaskets, use some dots of silicone sealant just to keep the
gasket in place, you don't need to cover the gaskets with sealant, they
should be installed dry. On the center seals use a thin coat of sealant
and a bit more where they connect to the side gaskets. Let the silicone
dry around 5 to 10 minutes and then carefully place the lower intake
into position. Use a flashlight or other light source to check gasket
alignment. If all is right install the lower bolts.
Here is the lower intake bolt tightening sequence :
Torque in 3 steps: 8 - 15 - 25
Re torque after running the engine.
Cover the intake ports so that nothing could get into them by accident.
Reinstall the heater core line, temp gauge sensor and fuel rails, use
a bit of engine oil to lubricate the O-ring injector seals. Connect
the injector wiring harness. Reinstall the distributor making sure the
alignment is ok.
By now you are just around 30 minutes away of starting the car, inspect
all your work before proceeding to the upper installation.
your new or stock throttle body into the upper intake, we did this when
we prepped the upper intake. Make sure the gasket aligns perfectly.
Install the bolts and tighten starting with the center ones working
your way outward. Torque to 30 pounds.
Hook all the rear vacuum lines: EGR, Fuel regulator, Cruise Control,
etc. Connect the temp sensor wiring, TPS, IAC, etc. Reconnect the plug
wires, distributor cap and coil. Take a look around and check for any
missing or loose connection.
Now you can connect the negative battery terminal and start filling
the radiator with your preferred coolant mix. I use 70 water/20 coolant
mix on summer and 50/50 on winter.
the engine and keep it running until in reaches operating temperature,
check for coolant leaks all around the lower intake. And check for oil
inside the coolant. If all is normal proceed to changing the oil and
filter. As we said this is a good safety measure as probably a bit of
coolant got to the oil when you removed the lower intake. If there is
just too much coolant in the oil you could have a leak in there.
Also important is to retighten the lower bolts after the engine has
A regular oil inspection is advised after a few days, just untighten
the pan bolts a bit and if coolant keeps showing then you have a problem
and you should go back and check the lower intake gaskets.
The complete procedure takes an experienced mechanic around 3 to 4
hours, it took me around 6 but that included some cleaning and detailing
of the engine.
The HP gain of this modification is around 15 hp if you keep the stock
60mm. By all means get a 65mm TB to get the full potential out of your
new intake. Aftermarket heads are 100% recommended, this is the biggest
restriction of the 5.0 engines.
Here's a chart showing flow numbers for several intake types: