How to Replace the Head Gasket in a 1965-1995 Mustang

Imagine this. You're driving through a beautiful forest along a winding mountain road in your Classic or Fox Body Mustang until your ride suddenly starts to sputter. Smoke billows out of your exhaust and your dash lights up like a Christmas tree. You pull over and pop your hood to find out that you blew your head gasket. This caused your engine to lose compression and, if left alone, could lead to significant damage or engine knock.

If something like this has happened to you, you need to replace the head gasket in your 1965-1995 Ford Mustang. Installing a new head gasket allows your engine to maintain proper compression and prevent overheating.

How to Replace the Head Gasket in a 1965-1995 Ford Mustang

Replacing the head gasket in a 1965-1995 Mustang with a Ford 302 or 351w V8 is a challenging process that requires a lot of technical knowledge to do properly. If you're a novice mechanic or just getting into Mustangs, it's probably a good idea to let a shop do the Mustang head gasket replacement. If you're still interested in doing it yourself, we used a Fel-Pro head gasket on our build.

Before installation, it's important to note that this guide is for head gaskets on 1965-1995 Mustangs with the 302 and 351W V8s. If you don't have a Classic or Fox Body Mustang, the installation process of a new head gasket could be drastically different.

Tools Needed

• Socket Wrench
• Socket Set
• Torque Wrench
• Combination Wrench Set
• Timing Light
• Abrasive Pad
• Drain Pan
• Pieces of Cardboard
• Gasket Sealer

Step 1: Drain Coolant

Before doing anything else, drain the coolant from the engine.

Step 2: Remove Engine Accessories

Start by removing the air cleaner, carburetor, and spark plug wires from your engine. Then, use a piece of cardboard and cover the intake to prevent anything from falling into the engine.

Step 3: Remove More Engine Components

Remove the valve covers, distributor, and coil. When removing the coil, pay attention to how the wires are hooked up to ensure that they go back to their proper location during reassembly.

Remove the distributor by taking off the hold-down clamp and pulling the distributor straight up. You may need to rotate the distributor back and forth to break it loose. Be sure to keep all of the fasteners in labeled bags to aid in reassembly.

Step 4: Continue Engine Disassembly

Remove the intake manifold, rocker arms, and pushrods. If your engine has stud-mounted adjustable rocker arms, you're going to need to loosen the inner hex head poly lock before removing the rocker arm nut. If your engine has pedestal-mounted rocker arms, simply remove the bolt in the center of the rocker arm. Remember to label everything to help you put everything back together correctly.

Step 5: Separate the Head from the Engine Block

Remove the head bolts, then separate the head from the engine block by pulling up on it. After you've removed the head, clean the mating surface on the engine block with an abrasive pad. Don't use a wire brush as the bristles can become lodged between the pistons and cylinder walls.

Step 6: Install Head Gasket

The Fel-Pro head gasket is directional, so we have to ensure that the word front is towards the timing cover. Not all head gaskets are directional, so make sure to check yours before installation.

After you've made sure it's facing the correct direction, place your head gasket into place and align it with the holes on the engine block.

Step 7: Reinstall Cylinder Head

Line the Mustang cylinder head up with the alignment dowel and gently slot it into place. Be sure not to force the head into place. Once the head is seated, reinstall the head bolts and torque them to the specs provided by the bolts' manufacturer.

Step 8: Rotate the Engine to Top Dead Center

Now, you're going to need to reinstall the Mustang rocker arms. It's important to remember that the first set of rocker arms must go back into the engine at top dead center (TDC). To do this, rotate the engine clockwise until you notice the intake lifter on cylinder #1 begins to move. Continue rotating the engine until the TDC mark on the harmonic balancer lines up with the timing pointer. Your engine is now at top dead center on cylinder #1.

Step 9: Install Mustang Pushrods and Rocker Arms

With your engine at top dead center for cylinder #1, insert the intake and exhaust Mustang pushrods into their respective locations. Then, reinstall the rocker arms as well.

Step 10: Set the Adjusting Nut

After you've reinstalled the pushrods and rocker arms, you'll need to set the adjusting nut on the intake valve rocker arm on cylinder #1. Slowly tighten the adjusting nut with one hand while rotating the pushrod with the other. Continue tightening the nut until you begin to feel drag while rotating the pushrod. This is zero lash.

Step 11: Set Preload on Hydraulic Lifter

Put a wrench on the adjusting nut and tighten it a half turn. Then, hold the adjusting nut with another wrench and tighten down the set screw inside of the adjusting nut. Follow this procedure on the exhaust valve of cylinder #1. Then, repeat this process for the other seven cylinders.

Rotate the engine 90 degrees clockwise to set up the next cylinder. This will set the next cylinder in the firing order at top dead center. Adjust those rocker arms and then rotate the engine clockwise another 90 degrees. Keep repeating this process until you've adjusted all of the rocker arms.

Here are the firing orders for the different engine options available for the 1965-1995 model years:

Step 12: Reinstall Intake Manifold

Before reinstalling the intake manifold, double-check and ensure that the mating surfaces on the block and manifold are completely free of old gasket material. Place a dab of gasket sealer around passages that will see water before installing the intake manifold. Put a dab of sealant where the cork gasket in the valley meets the gasket that seals the intake to the head.

Torque the Mustang intake bolts to 25 ft/lbs using the sequence on the diagram below.

Step 13: Reinstall Distributor

Set cylinder #1 to top dead center like you did in Step 8. Then, insert the distributor into the engine block. The rotor on the distributor should be pointing in the direction of where the cylinder #1 marking on the distributor cap will be when the cap is installed.

Step 14: Reinstall Spark Plug Wires

Plug the spark plugs wires back into place starting with cylinder #1 on the distributor cap and work your way through the firing order in a counterclockwise direction. See the diagram below for the cylinder numbers of a small block Ford V8.

Step 15: Reinstall Carburetor and Other Accessories

After you've plugged in all of the spark plug wires in the correct order, reinstall the carburetor, air cleaner, and other accessories to complete the engine rebuild. After you've got the engine back into your Mustang, be sure to refill your coolant and set your engine timing properly.

Congratulations, you're all done!

Ford 302 & 351w Head Gasket Replacement

While replacing the head gasket in your 1965-1995 Mustang isn't easy, it's essential if you want your engine to run healthily and effectively after a head gasket failure. If the Fel-Pro head gasket we used isn't for you, check out our other head gaskets and find the perfect one for your replacement project.