PerTronix D6681 User Manual

Corporate Office: PerTronix Inc. 440 E. Arrow Highway, San Dimas, California 91773 * Phone [phone] * FAX [phone] * www.dougsheaders.com

HEADER INSTALLATION INSTRUCTIONS

PART NUMBER: D6681

1996-04 Mustang 4.6 4 Valve

NOTE: Doug’s recommends that these headers be used in conjunction with part #D923

Aluminized Y Pipe to complete the installation.

NOTE: Oxygen Sensor simulators are required with this header due to removal of front catalytic

converters. Available from, RPM Outlet.com, 713 858-8059 part #RPM003020

PerTronix©

to realize the full potential of our good fit, please read and understand these instructions completely prior to starting work.
Check to make sure you received the proper parts for your application. The header number will be stamped on the engine

flange. If you are unsure you have received the proper parts call before you start work.
Be sure to work safe! Whenever you work under the vehicle be sure that it is located on level, solid ground and is supported

by adequate safety stands! Remember: Hot asphalt will not support most jack stands!
Many factors affect the installation of headers, some of which are broken or aftermarket motor mounts, accidents that impact the

configuration of the frame, and/or the installation of different engines or aftermarket cylinder heads.
Attention Customers breaking in new engines: Due to the extreme heat generated during the break-in process, the

appearance of the ceramic coating may be altered in certain areas. The protection characteristics and thermal barrier properties
of the coating is never compromised. It is recommended that a cast iron manifold or old set of headers be used for this process.

Notice: The coating of these headers can be marred or scratched during installation. If the header needs to be returned and is
damaged, you will be charged for recoat.

thanks you for choosing

DOUG’S HEADERS

, the best fitting, highest quality header on the market. In order

DISASSEMBLY

1. Disconnect the negative cable from the battery.

2. If a hoist is not available, raise the car 3 feet or higher and support with adequate jack
stands. Make sure the car is on a flat solid surface and is stable.

3. Remove the cold air inlet tube from both the air cleaner and the throttle body.

4. Disconnect the EGR tube from the throttle body.

5. If equipped, remove the upper shock tower brace. (mainly on Cobras or aftermarket)

6. Remove the bolt that holds the Oil Dipstick to the motor.

7. Remove the oil filter.

8. If equipped, remove the lower A Arm Brace. (Mainly on hard Top models).

9. Disconnect all 4 O2 sensor wire plugs. Remove the right side O2 sensor located next to
the starter motor.

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10. Disconnect the H Pipe from the factory manifold and rear exhaust section and remove
the H pipe from the car.

11. Disconnect the EGR Tube from the exhaust manifold.

12. The steering shaft needs to be disconnected from the steering rack. Wire the shaft so

that it can’t turn more than about 180 degrees after it is disconnected. If it goes much

more than that permanent damage can occur.

13. Remove the O2 sensor bracket from the driver’s side motor mount.

14. Place a jack under the oil pan, with a block of wood to prevent damage to the pan.

Remove the Driver’s side engine mount nut. Raise the motor far enough to remove the

motor mount. The motor mount needs to be modified as shown in Illustration B. The rear
motor mount stud needs to be modified as shown in Illustration A.

15. Slip the modified motor mount back into position but do not tighten.

16. On 96-97 Cars with A.I.R. remove the tube from the front of the driver’s side manifold.

17. With the motor still raised remove the stock manifold. Remove all the exhaust studs from
the head.

18. Lower the motor onto the motor mount.

19. On 96-98 cars with A.I.R. remove the tube from the front of the passenger side manifold.

20. Remove the starter motor.

21. Remove the engine mount nut and raise the passenger side of the motor approx 1”.

22. Remove the passenger side stock exhaust manifold. Remove all the exhaust studs from
the head. Lower the motor back on to the mount.

23. On stick shift models remove the clutch fork shield.

24. Remove the gaskets and any gasket material or any carbon deposits that remain on the
head surface. The use of a gasket removal agent will ease the removal of any gasket
material. Use care not to get debris into ports or spark plug holes.

INSTALLATION

1. Because of different A.I.R. configurations the headers must be prepared before
installation.

a. On 96-97 cars with A.I.R. insert a 3/8” drill bit in to the Driver and passenger side

front A.I.R. fittings and drill through the header tubes. Install the supplied fitting in

to each A.I.R. port. Install the supplied plug into the 1” tube that is between the

driver’s side #1 & #2 tubes and tighten.

b. On 1998 cars with A.I.R. insert a 3/8” drill bit into the Passenger side front A.I.R.

fittings and drill through the header tube. Install the supplied fitting in to the A.I.R.

port. Install the supplied plug into the 1” tube that is between the driver’s side #1 &

#2 tubes and tighten.

c. On 99-04 cars no A.I.R. system was used. Install the supplied plug into the 1” tube

that is between the driver’s side #1 & #2 tubes and tighten.

2. The Passenger side header must be installed first. Apply a small amount of Anti Seize to
all header bolts before starting.

3. Hold the gasket in place and install the supplied header bolts in the top two rear exhaust
bolt holes only. Only thread in a couple of threads.

4. Raise motor on the right side and slide the header into position.

5. On 96-98 A.I.R. cars start the tube into the header but do not fully tighten.

6. Lower the motor back on the motor mount. Slip the header under the two installed bolts
and then install the rear most lower bolt.

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7. Some of the remaining bolts will be accessible now. Start and snug them at this time.

8. Re-raise the right side and install the remaining bolts. Tighten all the passenger side bolts
at this time to 23 ft. lbs. Lower the motor but do not tighten the bolts at this time.

Driver’s Side

9. Swing the steering shaft back and to the left for access. You may need to unlock the
steering wheel to do this. DO NOT let the shaft spin more than 180 degrees.

10. Hold the gasket in place and install the supplied header bolts in the lower second
cylinder bolt and the upper rear cylinder bolt. Only thread in a couple of threads.

11. The driver’s side header is a two piece to allow installation. You will need to cut the
flange to separate. We have cut most of the way through to hold the header together
during shipping. Install the rear section first (3rd and 4th cylinder tubes) loosely into engine
compartment.

12. Slip the front section of the header into position, but NOT into the other half of the
header, swing the steering shaft back into place between the two halves of the header.

13. Slide the two sections of the header together at the slip joints. You may want to put a light
coating of High Temperature, Sensor Safe Silicone on the tubes before slipping together.

14. Raise the Driver’s side of the motor and remove the motor mount.

15. Install the rear most motor mount to frame bolt and screw it in until it is about ¼” from
being tight. Do Not install the motor mount yet.

16. On 96-97 cars with A.I.R., start the tube in to the header but do not tighten.

17. Slip the header flange over the header bolts that were installed in instruction 10. The
steering shaft should still be loose.

18. Install and snug all accessible header bolts.

19. Slip the motor mount under the installed frame bolt, install the two front bolts and tighten
all three. Lower the motor on to the motor mount

20. Install and tighten all remaining header bolts to a final torque of 23 ft. lbs.

21. Install the motor mount to engine nut and tighten. Tighten the passenger side motor
mount nut as well.

22. Reinstall the starter motor and the Oil filter.

23. Reinstall the steering Shaft and tighten. On Stick Shift cars, reinstall the clutch fork
shield.

24. Install the EGR tube to the Driver’s Side header. Tighten the A.I.R. fittings.

25. Install the rear O2 Sensors into the headers with a light coat of Anti Seize on the threads.
Use the supplied wire extensions.

26. Reinstall the EGR tube to the throttle body, along with the cold air intake.

27. Install the A Arm brace and shock tower brace if removed.

28. Doug’s recommends using part #D923 X Pipe to connect the exhaust to the rear catalytic
converter and tailpipes.

29. Check the oil level.

30. Connect the negative battery cable.

IMPORTANT CHECK LIST

Be sure that all brake lines and fuel lines are clear of headers and/or connector pipes.
All spark plug wires, battery cables, or other electrical components should be clear of

headers and/or connector pipes.

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If dipstick tube was removed, make sure it is installed properly and that the dipstick has

been replaced.

Double-check the tightness of all bolts including brackets and accessories.

STARTING THE ENGINE

Start the engine and allow it to warm up to operating temperature. Check for any unusual
noises or exhaust leaks. If every thing is OK, stop the engine and tighten all bolts while
the engine is still warm.
NOTE: Check the bolts periodically to make sure they have not loosened. Re-tighten
after the first 500 miles and then again at 1000 miles.

PARTS LIST

Qty Description

1 Left Side Header
1 Right Side Header
2 Header Gaskets
16 8mm 1.25X30mm Header Bolts
16 Header Star Washers
1 O2 Sensor Plug
2 O2 Sensor Extensions
2 2 1/2” Slip Reducers
2 Collector Band Clamps
2 18mm/20mm 1.5 A.I.R. Fittings
1 Doug’s Sticker

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