Corporate Office: PerTronix Inc. 440 E. Arrow Highway, San Dimas, California 91773 * Phone 909.599.5955 * FAX 909.599.6424 * www.dougsheaders.com
HEADER INSTALLATION INSTRUCTIONS
APPLICATION
1979-1993 FORD Mustang, 255-302W
PART NUMBER: D6671
PerTronix
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. Most installations require some
welding. If you are uncomfortable with welding operations, we recommend that you contact a professional exhaust system specialist
to install your new headers.
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 to
Note: The installation of this header requires that you use factory “Dual Hump”
transmission crossmember, which came on ’86-’89 Mustang 5.0 Liter models.
These Headers utilize two Slip Tubes on each side. Doug’s only makes a partial cut through
the flange during manufacturing and the customer MUST Cut the Flange the rest of the way in
order to install these headers
Part No. 0110-003059 Page 1 rev.1 8-23-2011 DSL
DISASSEMBLY
1. Disconnect the negative battery cable from the battery.
2. If a car lift is not available, raise the vehicle 2 feet or higher and support it with adequate safety
stands. Make sure the vehicle is on a flat solid surface and is stable.
3. Apply penetrating oil to all nuts and bolts to be removed.
4. Remove the air inlet assembly, diverter valve, hoses and oil dipstick tube.
5. Remove O2 sensors, if so equipped.
6. Unbolt head pipes from stock exhaust manifolds.
7. Remove spark plugs, stock exhaust manifolds.
8. Replace the spark plugs finger tight so debris will not get into the cylinders while cleaning the
head surface.
9. Clean the cylinder head surface which mates to the header. Use a gasket scraper and wire
brush to make sure that the surface is absolutely clean.
10. After cleaning is complete remove the spark plugs again.
ASSEMBLY
1. Apply anti-seize to all header bolts being used.
2. Apply a THIN film of Ultra Copper Hi-Temp Sensor-Safe Silicone Sealer to the header side of
the 2 supplied gaskets and glue them to the headers. Masking tape can be used to help stick
the gasket to the manifold.
3. Apply a THIN film of Ultra Copper Hi-Temp Sensor-Safe Silicone Sealer to the engine side of
the header gaskets.
4. If not using the O2 sensors, screw in the provided plugs.
5. Note: C-6/A40D Transmission only – Trim the ear on the right side of the transmission bell
housing (above the starter).
6. Starting from below, work the main header section up into place. Note: On some applications,
it may be necessary to loosen the transmission mount bolts and move the engine/transmission
aside for installation.
7. Start the header bolts but leave them loose.
8. Apply a small amount of THIN film of Ultra Copper Hi-Temp Sensor-Safe Silicone Sealer to the
slip joints.
9. From above, install the remaining header tubes and bolts. Note: carefully bend/move the brake
line to clear the tube for the #8 cylinder.
10. Tighten all bolts evenly.
11. Re-install engine oil dipstick tube and dipstick. Note: It may be necessary to bend the dipstick
tube in order to clear the headers and line up with the mounting tab.
12. Install the diverter valve, hoses and air inlet assembly.
13. Tighten the header bolts evenly to a final torque of approximately 25 ft. lbs.
14. Reinstall spark plugs and plug wires.
15. Install reducers and attach exhaust system to reducers.
16. Install O2 sensors, if so equipped.
17. Make sure all of the other fasteners are tightened.
18. Connect the negative battery cable.
Part No. 0110-003059 Page 2 rev.1 8-23-2011 DSL
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.
If removed, make sure the dipstick is installed properly and that it has been replaced.
Double-check the tightness of all bolts including brackets and accessories.
Perform these checks again after the first 1000 miles.
Check clearance and tightness of front driveshaft.
START THE ENGINE
Start the engine and allow it to warm up to operating temperature.
Caution! Hot parts! Wear protective clothing as needed.
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 Right side header
1 Left side header
2 Header gaskets
2 Collector gaskets
2 Reducers
2 O2 sensor plugs
1 Decal:
1 Hardware kit:
16 3/8”-16 x 1” flanged header bolts
22 3/8” lock-washer
6 3/8”-16 x 1-1/4” hex bolts
6 3/8” hex nuts
DOUG’S HEADERS
Part No. 0110-003059 Page 3 rev.1 8-23-2011 DSL
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