DOUG S HEADERS D305 1 5/8 Inch 4-Tube Shorty Header Chevrolet

Installation Instructions & Warranty Information

D300Y ~ 1963-87 Chevy 1/2, 3/4, 1 ton 2 & 4WD
1963-91 Blazer, Suburban
1973-91 Crew Cab 2 & 4WD
265-400 Small Block Engines Long Tube Tri Y Headers

PERTRONIX PERFORMANCE BRANDS EMISSIONS CODES
This product Is Legal for use on Pre-Pollution Controlled Vehicles. It is legal for use on all vehicles produced Before Emissions Control Regulations were imposed. These are considered Uncontrolled Vehicles and are defined as follows; 1965 and Older US Manufactured California Certified Vehicles 1967 and Older US Manufactured Federally Certified Vahines 1967 and Older Foreign Manufactured Vehicles REVJ/202

PERTRONIX PERFORMANCE BRANDS EMISSIONS CODES
This Product is LEGAL for Closed Course Competition use or Pre-Emissions Controlled Vehicles ONLY. It is Not Legal for use on any Emissions Controlled Vehicle for Street or Off Highway use. REV/2022

WARNING: This product can expose you to chemicals including Lead, Nickel, Cadmium and Chromium which are known to the 5tate of California to cause cancer and birth defects are other reproductive harm. For more information go to www.P65Warnings.ca.gov

PLEASE READ BEFORE PROCEEDING

PerTronix thanks you for choosing a Doug’s Headers Product. To realize the potential of Doug’s Headers engineering and excellent fit, Please Read and Understand these instructions completely prior to starting the installation. Check that you received all the parts listed on the parts list, if you have any concerns please contact PerTronix before continuing. Headers will have the part number stamped in the flange. Many factors affect he installation of exhaust headers, including whom or aftermarket motor mounts, previous accident damage, aftermarket cylinder heads that may have relocated port or spark plug locations, suspension and steering changes, sagging of original unibody structures due to age

Coating Notes: Coatings can be marred during installation if you are not careful.
If you are breaking in a new motor, the extreme heat can alter the appearance of the coating and this is not a warranty issue.
We recommend breaking in new motors with stock manifolds or an old set of headers.
We use sealing beads on all our headers.
The raised bead creates a better seal virtually eliminating leaks if installed properly. It is important to install all header bolts lightly snug and then tighten to factory torque specs starting in the center and working outward.
Before starting, allow the vehicle to cool, disconnect the battery. and spray a penetrating oil on all hardware and fittings that will need to be removed. Once you remove your manifold, dean the sealing surface on the head of any old gasket debris or carbon build up.
Work Smart- Work Safe! Most Header and Exhaust Installation are best performed on a lift. If a lift is not available, raise the vehicle and support on quality Jack Stands on level ground. Do not rely on a jack!

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 with adequate safety stands. Make sure the vehicle is on a flat solid surface and is stable.
3. Remove bolts attaching head pipes stock manifolds and move the stock headpoles out of the way for header installation.
4. Remove the Oil Dipstick Tube, Starter, Clutch linkage (on std trans cars), Oil Filter, and Oil Filter Adapter.
5. Remove the Spark Plugs Wires and spark Plugs.
6. If the A/C Compressor or Alternator are mounted to the manifolds, remove these items.
7. Remove A.I.R. injection tubes if equipped. Remove the stock Exhaust manifolds.
8. Remove any remaining gasket or carbon deposits from the head surface. T
9. After cleaning is complete remove the spark plugs again.

ASSEMBLY

1. Starting on the Driver’s side, slip the header roughly into position from the bottom.

2. Slip the gasket in place and install the supplied header bolts and tighten.

3. Replace the Oil Filter, the Oil Dipstick Tube, and Clutch Linkage

4. NOTE: 1967 Models, Modify the clutch linkage as shown in Illustration A.
   Some models may need to modify the shift linkage per Illustration B.
   Models with Alternator on the Driver’s side may need to purchase Alt Bracket

   H7606 and possibly #H7607.

   Models with Power Steering Bracket on Driver’s side may need to fabricate spacer as shown in Illustration C.
   Models with A/C Compressor on Driver’s side may need to purchase bracket part

   H7608, see Illustration D.

5. Slip the Passenger side header into position from the bottom.

6. Slip the gasket in place and install the supplied header bolts leaving them loose for access to the starter.

7. Slip the starter back in to place with the header loose, and tighten the starter bolts. Carefully reroute the wires to the starter ensuring that they are away from the header. Then tighten all header bolts evenly

8. Check transmission cooler lines and move away from header as necessary.

9. Re install spark plugs and wires, making sure the wires are clear of the header tubes.

10. On SP and DP models install the A.I.R. injection tubes.

11. If reusing the existing exhaust system cut and modify as necessary to connect to the headers using the Doug’s Reducers.

12. Connect the negative battery cable.

IMPORTANT CHECK LIST

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

START THE ENGINE

Start the engine and allow it to warm up to operating temperature. Check for any unusual noises or exhaust leaks. If everything 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

• 1 Left side header
• 2 Header gasket
• 12 Bolt, header, flanged, 3/8”-16 x 1”
• 20 Lock-washer, 3/8”
• 6 Nut, hex, 3/8”-16
• 1 Right side header
• 2 Reducer gasket
• 2 Bolt, header, flanged, 3/8” -16 x ¾”
• 6 Hex head cap screw, 3/8”-16 x 1-1/4”

DOUGS IIEADES 1IWITED WARRANTY

All Doug’s Headers and Exhaust products are guaranteed, to the original purchaser, to be free of defects in material and workmanship for anew year from date of purchase. This warranty covers the replacement or repair of the product and does not cover the cost of removal and installation, customer applied coatings, or Any discoloration or corrosion of finished surfaces.

Damage or product failure resulting from collision, improper installation, off road use, road hazards, the use of exhaust insulating wrap, or rust occurring after installation is not covered by the warranty. This warranty extends only to the original purchaser.

Should a part be deemed defective, it should be returned to the original selling retailer and must be accompanied by the sales receipt. If there is no retailer in your area, contact PerTronix direct for a return authorization and return the part prepaid to the factory for inspection. PerTronlx reserves the rights to replace or repair the alleged defect live part and return the part freight collect.

Read User Manual Online (PDF format)

Download This Manual (PDF format)

Download this manual  >>