How To Install Long Tube Headers

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MAC Long Tube Header Installation on 99+ v6 Mustang

Original article written by TR2002

Image:Headers 002.jpg This article details the installation of MAC Long Tube Headers on a 99+ V6 Mustang

I installed 99 model LT headers on my 2002 model car with little modification needed.

This write-up covers everything from test fitting and troubleshooting fitment problems, and should be accurate for ALL model year installations of MAC long tube headers.

This specific write up was written from my experience installing the 99 model LT headers on a 2002 year car with a T-5 Manual transmission.

For 4R70W applications, this guide will also work, but the clearance issues may be slightly different. Most automatic transmission LT header installs will require clearance being made in additional locations as well as the locations listed in this guide. Those locations will be evident while you are going through the TEST FIT process of this guide. Make your adjustments where needed depending on your situation.

For vehicles equipped with air injection, or advanced emissions equipment, the following will answer your questions.

If your vehicle has Air Injection, a form of emissions control on some mustangs, then you must order MAC LT headers which are equipped with air injection ports. These headers will have 2 bungs on each header, located on the number 1 and 4 primary tubes. To use your air injection equipment you must have the MAC LT headers designed for use with air injection.

If you have MAC LT headers which do not have air injection bungs, and your vehicle does have air injection, there are 4 options for you.

• Option 1: Return the headers and request headers equipped with air injection bungs.

• Option 2: Delete the air injection system by removing the smog pump and air injection tubing. <not possible for passing emissions in some states>. This will require a chip or flash of the EEC to disable some emissions features in the EEC system to avoid a CEL <check engine light> from being turned on.

• Option 3: Have an exhaust shop or capable shop of the like, custom fabricate air injection bungs onto your LT headers which are not equipped with air injection bungs already.

• Option 4: Cap the air injection tubing ports and leave the air injection equipment installed and have a chip or flash that will disable the function of this equipment while leaving it installed.

[edit] Choosing to Upgrade

There has been a lot of questions as to when MAC Long Tube headers would be a good choice in upgrades from stock exhaust manifolds/headers. The answer is anytime. Long Tube headers will give performance gains to stock engines as well as power adder engines such as supercharged and nitrous. While the stock V6 mustang will show moderate gains said to be in the range of 8-15 rear wheel horsepower and torque, power adder cars show more evident gains.

Long Tube headers benefit from a free flowing top end. Ported cylinder heads and intakes as well as larger camshafts. The added intake would be complimented with a better flowing exhaust, and Long Tube headers offer just that. As with a free flowing top end, Long Tube headers are well matched with power adders, and have shown to provide as much as 30 rear wheel horsepower on cars equipped with centrifugal superchargers.

Opposed to Long Tube headers, you have the option of short tube, or equal length headers. Short, also known as "shortie headers" and equal length headers are better suited to a roots type superchargers and are most always used when fabricating a turbocharger system on a V6 mustang. Shortie headers provide added gains in torque.

On mostly stock, or bolt on modded cars, LT headers and open exhaust will result in a shift of the engines power band. This shift in the power band is due to the loss of back pressure and exhaust scavenging. The engines torque band will be moved higher into the RPM range. With a stock engine, peak torque is usually made around 2500 RPM. With the free exhaust the peak torque could start being made at 3000 to 3500 RPM. Over all horse power will increase throughout the RPM range with the application of a free flowing exhaust.

My setup included the following:

• MAC 99 model year Long Tube Headers with air injection ports.
• MAC 2.5" Off Road H pipe for Long Tube Headers
• MAC 2.5" GT Flowpath Catback with 3" Stainless Steel tips.

I have had my EGR deleted before this install so I cannot cover the EGR setup install. It is as simple as just threading the EGR tube onto the EGR bung on the passenger side LT header though. Just thread it on with some RTV sealant on the threads and you should be good to go! I also explained the capping of air injection ports on the 99 model headers for use on cars without the air injection <California emissions> type equipment.

Compatability

• 99 model headers WILL work on 2000+ vehicles!

• 94-98 model LT headers will work on 99+ vehicles.

• 99+ LT headers will work on 94-98 vehicles.

[edit] Tools Needed

• 13mm Deep well socket. 3/8 " or 1/4" drive is best due to tight working space
• Assortment of extensions from 3" to 12" in length
• WD-40
• 13mm Wrench open end/closed end type
• 5mm socket <for stock stud removal and install>
• Flat head and cross tip screw driver's
• 4 jack stands and a jack
• 7/8 Wrench or 02 sensor socket
• 02 sensor extenders <or you can extent the EEC wiring harness>
• butt splices or solder, soldering iron and 18 gauge copper core wire to extend 02 sensor plug on EEC harness
• locking header bolts <suggested but not required>
• 2 new FelPro or Ford exhaust manifold gaskets <you can reuse stock, but you may have leaks!>
• Anti Seize lubricant <for spark plugs and header studs>
• Black high temp RTV silicone <optional> you can put this on your gaskets or not. Some do, some don't. I did not and I do not have leaks. It usually burns off anyway, but will still work to seal the gasket some.
• A helper to hold the LT headers in place to get the first few bolts started.
• 2x4 piece of wood 15" in length <for header template>
• hammer to make header template
• Wire brush to clean mating surfaces
• carb cleaner or brake cleaner to clean mating surfaces
• rags

[edit] Time to complete install

7 hours with breaks and all needed tools at hand, as well as 1 helper.

[edit] Removal of Stock Headers - Part 1: Making room

Jack the car up on all 4 corners as high as you can get it and support it on jack stands. This will allow you to remove the old exhaust easily. You will need a long 12" extension to remove the factory Y pipe and cat assembly from the ball joint connection to the stock headers. Once the stock catalytic converter and Y pipe are removed, you can start on removing the stock headers. Don't forget to disconnect the 4 oxygen sensors from the stock pipe!

Now to remove the stock headers, you must remove some things that are in the way. First, the CAI, or stock airtube and airbox assembly must go.

Then you want to remove all 6 spark plugs and spark plug wires. Mark the plug wires so you don't put them back on the wrong plug when re-installing! Next you will need to make some room on the driver side.

Unbolt the brake master cylinder from the power brake booster <the big black drum thing on the driver side firewall> and gently pull it off the studs on the brake booster. Now pull it as close to the strut tower as you possibly can and zip tie it there tightly. This may not seem like a lot of room, but trust me, every centimeter helps, and moving that master cylinder just that much will give you a lot of room to work on that header.

Next unbolt the dip stick tube. You can work around it, but it is already a tight space, and that tube makes it rather hard to get to some header bolts, and is always in the way. I removed the dip stick tube from the car. Be very careful when doing this though, you don't want to break it off in the engine block. It is a tough piece, but it can break off. You can bend it at a 90 degree angle right where it is closest to the header to help pull it out. You want to pull it straight out, don't angle it and pull it. It will pop out of there with a little effort.

Next unbolt the clutch cable <if equipped with T-5 Transmission> from the frame just below the fuse box. There is a bracket there that holds the clutch cable in a solid mounting position. Now pull it up and over as far out of the way as you can get it. Zip tie it anywhere you can to keep it out of the way. I zip tied mine to the brake lines coming off the master cylinder. It worked well there.

Now you should have enough room to get at the header bolts and studs.

[edit] Removal of Stock Headers - Part 2: Removal

Now you will see the stock headers. They are held on by 6 13mm bolts on each side of the engine. The 13mm bolts are threaded onto 6 studs. First spray each of these bolts with a small shot of WD-40. Don't go crazy, just hit the bolt and the threads on each stud. Do this for both sides. Next, you will need your 13mm deep well socket and your 13mm wrench. Some of the bolts you can get the socket onto with an extension, some you don't need the extension, some you can only get at with the wrench. The front couple bolts should be easy. The rear bolts you will need your extension and your wrench. Use what ever tool you can get onto each bolt in its position, and break the bolts free. Take only the 6 passenger side header nuts off of the studs. We will use these later for our header template! Leave the nuts ON the driver side studs and only loosen the nuts about 5 threads to relieve pressure from the stock headers.

Next, take your 5mm socket and a 2" extension and carefully break each header stud loose from its bore. The stock studs are a 5mm hex head so you can use your socket to remove them. Have your helper go under the car and hold the stock header up while you remove the studs. Leave the nuts on the driver side studs if you are going to reuse the studs. NOW PAY ATTENTION. The studs are different in length. On the passenger side, the longer studs are towards the front, and the shorter studs are toward the rear of the engine. On the driver side header, the longer studs are towards the rear of the engine and the shorter are towards the front. You want to put those studs back where they came from, so MARK THEM. How important this is I do not know, but they are like that for a reason. Once you have all the studs removed and marked, remove the stock header and gasket from the engine. Keep it handy. You will need it to make the LT header fitting template later on!

Now go to the drivers side and repeat the process of removing the stock header. Remember to note the location and length of the stock header studs.

OK, you should now have the stock headers off the heads. Let's move on, shall we?

[edit] Preparing the Heads for Clean-Mating of LT Headers

OK, now that you have the stock headers off the heads, look in there at the exhaust ports on the heads. You will see there is a black build up of carbon from exhaust gas. That all needs cleaned off of there. Use your carb/brake cleaner and spray it on a rag. Get that rag really wet with it. Now wipe the exhaust ports and header mating surface with the rag and get them really wet with the carb/brake cleaner. Quickly take your wire brush to each one and get them as clean as you possibly can. They should be free of all black carbon and shine pretty good when they are cleaned. It is important to get them as clean as possible to ensure a good gasket seal and prevent leaks! Once both are cleaned, we will move on to preparing the MAC LT headers for install.

[edit] Preparing MAC LT headers for Installation - Part 1: Test Fitting

Now MAC headers are pretty good, but, they are known to be a rough fit on our cars! Some test fitting is a good idea to help ease installation and prevent cabin noise and rubbing on the chassis, k member and starter. We will now test fit each header onto the car.

First, get your helper to go under the car with the passenger side header.

The passenger side LT headers are known to rub the following:

• starter
• strut tower
• k-member
• motor mount

Mine rubbed the starter and motor mount. Have no fear, there is a way to fix this!

Have your helper feed the header up from under the car. When it is in place to be bolted on, get 2 of your stock header studs. Place 1 header stud at one end, and the other at the other end. This will keep the header in place as it would be when installed. Don't tighten the stud down with any torque. Just snug it up so it is just barely tight against the head. Now get under the car and look at the header position. Note any places where it contacts the car. Look around the areas I pointed out earlier and see if it is contacting anywhere. If it is, mark these areas with a pencil and then remove the header.

Carefully take a hammer and bang the contact areas out to allow clearance of these trouble areas. Don't beat them to death!! Just pound it out enough to clear the contact areas.

After you think you have it beaten out to clear, test fit it again and note any clearance issues. Once the passenger side header is clear of contact, repeat the process for the driver side.

The driver side header has been known to rub the following:

• K-member
• motor mount
• steering shaft

Test fit and make the needed adjustments to the driver side header, then test fit again to ensure clearance.

Once they are both clear, we can continue to part 2 of preparation of your LT headers.

[edit] Preparing LT Headers for Installation - Part 2: Creating Header Template for Alignment

Now, some LT headers won't match up to the heads' header stud holes! Mine didn't! They needed some work to get a good alignment to ease threading the header studs/bolts. Now we will talk about that, and how to make them fit like a charm!

First, get your stock headers that you removed. Next get your 2x4x15 piece of wood. Get your 6 stock header studs with the bolts removed. Now, place the stock header onto the 2x4x15 piece of wood, and use a pencil to go around the inside of the holes on the flanges and trace the position of each hole on each flange onto the 2x4x15. This will make a template of the spacing in the stock headers that match the header stud holes on the heads. Now, use a cross tip screw driver to punch a starter hole in the center of each of your pencil marked circles. Now tap the stock header studs into the 2x4x15 with your hammer, and then use your 5mm socket to screw them in snug. Make sure you screw them in as straight as possible. We don't want any angle on these studs. Once you have the 6 header studs screwed into the 2x4x15, you have made your template for the passenger AND driver side LT header.

Next we are going to fit the LT headers onto that template.

Get both your LT headers. Try to slide each of them onto the header studs on your template. If they will fit on, and slide all the way to mate up to the 2x4x15 then you're good to go, and got lucky! If not, then bend the primary tubes by hand till they will fit over the studs and slide all the way down onto the 2x4x15 with ease. You do not want them to be a tight fit over any of the studs. You want them to slide on easily and go all the way down and mate up to the 2x4x15!

I drilled out the holes on the flanges of the LT headers to the next size to ensure plenty of clearance for threading the studs/bolts back into the heads. You can do this as well to help fitment.

Fit both headers onto the template and make sure they slide free and easy down onto each stud and mate cleanly onto the 2x4x15. Once this is done, the headers are ready to be installed!

Now if you have 99 model LT headers and a 2000+ car without air injection, you will need to cap off the air injection ports on the LT headers. Just get 2 brass caps from your local hardware store, and put JB Kwik weld in them on the threads and thread them on. Let the JB Kwik weld dry and they are sealed.

[edit] Installing the LT headers

Apply a little anti seize lubricant to all the header stud threads that go into the heads!

Before we get started here, if you are going to extend your EEC wiring harness passenger side 02 sensor plug, do it now. Do not cut the 02 sensor wires and extend those. Extend the plug on the harness by 10". You can use butt splices or solder. Either will work. On the driver side, if you pull the push pins out and create slack in the harness behind the engine, the driver side front 02 sensor will reach the bung on the LT header. Mine did, and I didn't have to extend anything there. Just the passenger side harness plug needed extended. I did this with 18 gauge copper core wire and butt splices. OK, so now you have the LT headers test fitted and banged out for clearance, and test fitted to your template for correct alignment to your header stud holes on your heads. Now comes the fun of threading all those header studs/bolts!

First, have your helper go under the passenger side with the LT header. Have them feed it up through the bottom and align it to the head. Thread all your 6 bolts back onto the stock studs. You should have them removed from your template by now. Now start by placing your gasket into position and putting the front stud through the header flange hole and the gasket hole. Don't forget the anti-seize on the threads of the header studs! Just use a little bit on them. After all, we are threading these into aluminum heads! Anti-seize is always good for using steel threads into aluminum! Now, finger thread the front stud into the head about 5-6 turns. Don't use air or a wrench or you may cross thread the hole! Once you got the front stud threaded, thread the rear most stud in the same fashion. Don't forget to go through the gasket hole!

Now that you have the front and rear stud in, the header will hang there, and your helper can take a rest. It's no fun holding that header in place!

Now snug up the front and rear stud into the head. Don't use a lot of torque here. Just snug is good. Now snug your header bolt down and bring the LT header snug against the head. Now place the rest of your header studs into their holes on the heads. It's a bit of work but you'll get it. Snug each stud down into the hole on the head and then snug your header bolts down onto the headers. Do not torque any of them down yet.

Once you get all the bolts snug onto the header, you can torque them down. Start with the center flange, and work out towards the ends going back and forth. You don't want to torque them in a straight line. The header bolts should be torqued to 35 ft lbs, but good luck getting a TQ wrench in there. Just torque them down nice and tight and put that extra 1/2 turn on each after they are "tight". That should be fine. This is what I did and they are secure and don't leak.

Now go to the driver side and repeat the process of finger threading each stud first, then snug the studs, then snug the bolts then TQ the bolts in a back and forth pattern. Remember, not straight across in a line!

You're DONE!! Here are some things to consider:

• Don't forget your anti-seize on your spark plug threads! Just a light coating will do it!

• After you have each of the headers torqued down and on the car good and secure, you can re-attach your 02 sensors. It is easier to screw them into the bung on the LT header collector first then plug them into the harness.

• Put everything back together the way it came apart. The dipstick tube is a pain to get back in. It goes between the motor mount and the block. You can feel the hole with your finger. Have your helper push it while you align it to the hole in the block. You must put it back in as the o-ring on the tube prevents oil from leaking out of the block while the engine is running. Make sure it is in all the way.

I hope this was helpful, and good luck with your installation!

TR