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How to Install a Professional Products Typhoon Intake Manifold on Your 1986-1995 5.0L Mustang

Installation Time

4 hours

American Muscle
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General Notes:Please review these specific instructions and the enclosed General Instructions before starting to install your new Power Plus induction system.

EGR System- This manifold will accept the stock Ford EGR equipment. This manifold is 50-state street legal on the listed applications.

Recommended Additional Parts- This manifold is designed for high performance street applications and is generally suitable for bracket racing, nitrous installations, and supercharged applications.

We recommend the use of a 70mm Throttle Body(Professional Products #69201 for 1986-'93, or Professional Products # 69211 for 1994-'95. Early models require a #69501EGR Plate) with this manifold. 1994-'95 installations also require a Power Plus Throttle Body Adapter (#54150 polished, #54151satin) and an aftermarket Strut Tower Brace (Ford Racing #M-20202-A51 or Edelbrock #5225). 1994-’95 installations also require a special fitting; Power Plus #54152.

Use of Power Plus Plenum on other manifolds- The PowerPlus Upper Plenum #54124/#54125 can be used to replace the Upper Plenum on an Edelbrock Performer #3821 or Edelbrock Performer RPM #7126 if you want the polished appearance available from Power Plus.

50-State Street Legal- This manifold assembly is 50-state street legal for 1986-’95 Ford Mustangs with 5.0L V8 engines.

Installation Instructions

Important Notice Before You Start- This manifold kit is designed to fit a wide range of engines. The vacuum hoses and other connections may vary from year to year on these various engines. Our manifold is designed to accommodate all of the different engine configurations. As a result, you may not use all of the fittings or vacuum ports on this manifold.

When you begin to disassemble your current engine, please pay special attention to all the various hose connections and mark or tag them in some way so that you can properly reconnect them to your new manifold. Plug any unused vacuum ports.

This is very important.The majority of the tech calls we receive are due to confusion on how to hook up these various lines. It is impossible for our tech people to help because of all the different configurations Ford has used. So it is critical that you keep track of the hose connections yourself before taking them apart.

Removing Original Manifold:

1. Disconnect the negative cable from the battery. Drain coolant. (Not required if installing Upper Plenum only.)

2. Disconnect electrical connections, linkages, control cables, vacuum hoses, ventilation hoses, and coolant hoses at throttle body and manifold. Note: Do not disconnect fuel lines unless absolutely necessary. Special steps and tools are required to re-connect fuel lines.

3. Remove distributor cap with wires intact. Mark a reference point on distributor for rotor alignment during re-installation. Remove retaining bolt and distributor.

4. Remove cover plates, retaining bolts, upper intake manifold and gasket.

Note:If you are installing only the Power Plus Upper Plenum, proceed to Step #7 of the "Installing New Manifold” Instructions.

5. Remove accessory brackets attached to lower manifold. Remove heater tube assembly from lower manifold. Remove retaining bolts attaching manifold to heads. Remove manifold, gaskets and seals.

Installing New Manifold:

1. Clean all gasket surfaces on head and block. Apply a 1/4-inch bead of RTV silicone sealer at junction of cylinder head and block surface before gaskets are installed.

2. Note: Fel-Pro #1250 Intake Gasket Set is highly recommended for street use. Non-embossed high performance gaskets will deteriorate in street driving conditions. Apply gasket sealant to the manifold mating surfaces and the head surfaces where gaskets contact them.

3. Install intake manifold gaskets on each head.

4. We recommend eliminating the end seals and instead use 1/4-inch high bead of RTV silicone sealant across the front and rear block end seal surfaces, overlapping the intake gaskets.

5. Install lower intake manifold and retaining bolts. Torque bolts to 15-18 lb. ft. Follow bolt tightening sequence in Figure#1. See back of this flyer.

6. Install injectors and fuel rails to new manifold. Use new "O"-rings. Use only specified fuel resistant brown "O"-rings. Lightly coat "O"-rings with clean engine oil before installing. Clean fittings and replace garter spring if necessary.

7. Install Upper Plenum and gasket. Do not use any sealant on this gasket. Use supplied bolts and studs as shown in Figure #1. Note: Upper Plenum must be positioned so that throttle body is not on driver's side of vehicle. It must be on passenger’s side. Note: If you install a Power Plus Upper Plenum on an Edelbrock early Performer Manifold (#3821),there are two bolt holes that are not used. See Figure #1.Do not over tighten Upper Plenum to Base Manifold. Use a short box or open end wrench only

8. The stock vacuum tree has been eliminated. Use the 3/8"NPT 90° elbow and 3/8" NPT hose fitting in the rear of the Upper Plenum. Fit the 1/8" NPT to 3/16" hose fitting in the rear facing 1/8" NPT boss on the crossover (next to EGR plate). Use the supplied vacuum line and "tee" to feed the fuel pressure regulator and the MAP sensor from this source.

9. Remove the original throttle valve/EGR plate studs from the stock manifold and install in the new one. To re-install remaining components, reverse the removal procedure. Adjust all control cables. If your vehicle has an automatic transmission and you are using a Professional Products Throttle Body, refer to throttle body instructions regarding transmission throttle valve cable linkage adjustments. Fill cooling system with coolant. Connect battery cable.

10. Retorquing the manifold bolts is recommended after starting the engine, bringing it to operating temperature, and shutting it down several times. Retorque when engine is cold.

A5/16-18 X 1-1/4” bolt
B1-3/8” Stud
C5/16-18 X 4-3/4” bolt
Dnot used
E5/16-18 X 4-3/4” bolt
F1-3/8” Stud
G5/16-18 X 1-1/4” bolt
H5/16-18 X 1-1/4” bolt
Inot used
J5/16-18 X 1-1/4” bolt

*Note:When installing the Professional Products Upper Plenum #54124 or #54125 on an Edelbrock early Performer #3821, these two bolt holes are not used.

Kit Contents - 54020/54021

  • 1 plenum cover gasket
  • 1 base-to-upper gasket
  • 1 10” length 5/32” vacuum line
  • 2 5/16”-24 hex nuts
  • 2 5/16” split lock washers
  • 2 5/16” x 1-3/8” stud
  • 2 5/16”-18 x 4-3/4” flange head bolts
  • 4 5/16”-18 x 1-1/4” flange head bolts
  • 1 3/8” pipe plugs
  • 2 1/8” pipe plugs
  • 1 3/16” vacuum tee fitting
  • 1 3/8” pipe 90° fitting
  • 1 3/8” pipe to 3/8” hose fitting
  • 1 1/8” pipe to 3/16” hose fitting
  • 1 1/8” pipe to 3/8” hose fitting

Power Plus Mustang 5.0 EFI
Manifold #54020/#54021
Power PLus Mustang 5.0 Upper Plenum
Fits: 1986 to 1995 Ford 5.0L V8, EGR
Note: These instructions are in addition to the General Instructions also packaged with this manifold.

This guide applies to Vehicle years: 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995 and Submodels: Cobra, Foxbody, GT