Mark Houlahan
Tech Editor, Mustang Monthly
April 28, 2002

If you're a regular reader of my automotive babbling, you're sure to remember the 5.0 Basics arti-cles in the August ("Air Apparent," p. 151) and September ("Getting Shafted," p. 153) '03 issues. We worked on Brian Wesche's '89 GT, enhancing its breathing capabilities via an Edelbrock intake and Crane cam. Now we plan to tie all the upgrades together via the installation of Edelbrock's Performer 5.0 cylinder heads.

For many of you, installing cylinder heads is a new adventure. That's why we're here to hold your hand. There are likely quite a few of our readers who can swap cylinder heads in two hours in the trailer, at the track, in the rain, and with no air tools--but that's not who this article is for. So, if you've thought about what it takes to crack open a 5.0 and do some serious work, we have the information you need.

When we began working on Brian's Mustang, it was already adorned withJBA Shorty headers, a Flowmaster exhaust, underdrive pulleys, andgears.The car was a blast to drive. Then we dropped an EdelbrockPerformer 5.0 intake into the mix. These parts are all included in thebaseline dyno testing. If you remember Brian's cam swap ("GettingShafted," Sept. '03, p. 153), the GT made 213 hp and 258 lb-ft of torqueon Lugo Performance's Mustang Dyno. After swapping the heads for Brian,we had him take his GT back to Lugo's for another spin on the rollers tosee what the new heads did for the combination. The GT walked away withanother 16 hp. Brian says the car is more fun to drive now, and thatwith the heads in place he can hear the cam in the exhaust more now,which he likes. With a larger throttle body (he's running a used 65mm),a mass air meter, and some tuning on the fuel system, we're sure Briancould see more horsepower out of this package.

Horse Sense: Cylinder-head gaskets are not cheap (for the good ones, at least), and once the engine is back together they're not easy to replace. So, make sure you have the correct cylinder-head gasket or use the gasket recommended by the cylinder-head manufacturer. Ensure the block surface is prepared properly for a good gasket seal and that the gaskets are positioned correctly on the block.

Of course, in only four or five pages we can't show you every nut and bolt, so we always encourage the ownership and use of a good shop manual. Whether you acquire it from Ford or the aftermarket, a shop manual will help with some of the minor details and the ever-important torque specs. Just follow the directions, work methodically, and you shouldn't have any problems. Sure, the first time you yank a set of cylinder heads it might take you all weekend, but with experience comes efficiency, and you'll soon be helping your friends swap cylinder heads in half the time.

For Brian's GT, we chose Edelbrock Performer 5.0 cylinder heads for a simple bolt-on that would accept all the modifications that have already been added to his car. These heads accept stock valvetrain components, stock-bolt-pattern headers, and all Ford intake manifolds. To minimize clean-up time, we also ordered new head bolts, head-bolt washers, and intake bolts.

Edelbrock has been building cylinder heads for many years. The oneswe're using are the Performer 5.0s (PN 6037). These heads come fullyassembled and feature one-piece, stainless steel, 1.90-inch intake and1.60-inch exhaust valves that are swirl- polished and have undercutvalve stems for improved airflow. They also feature hardened springseats, with a spring package that can handle up to 0.575 inch of camlift, and Heli-Coil thread inserts in all major threaded openings forstrength. The heads are available for around $1,100 from most mail-orderoutfits.
1. Since removing any item bolted to the old heads is required, you'llneed to remove the cooling fan and fan shroud for working room. The fanis secured with four 7/16-inch bolts and the shroud has two 7/16-inchbolts. Remove the fan and shroud together from the engine compartment.Drain the coolant from the radiator into a clean container.
2. The A/C compressor will have to be moved out of the workspace toaccess the driver-side cylinder head. Remove the three 9/16-inch nutsretaining the compressor support bracket to the water pump, as well asthe two 13mm bolts at the rear of the A/C compressor and the large nutand 9/16-inch bolt under the compressor. This will allow the compressorto be swung over to the passenger-side fender area. Use a fender coveror a folded T-shirt to protect the paint surface.
3. After the A/C compressor has been removed from the large mountingstud at the front of the driver-side cylinder head, remove thecompressor mounting bracket and the stud. A single bolt retains thebracket. Once the bracket is removed, the stud can be extricated fromthe cylinder head with a stud remover (shown here) or a sturdy set oflocking pliers.
4. The passenger-side cylinder-head face is home to the alternatormounting bracket and the Thermactor air pump. This GT was missing itsThermactor pump and controls, so the only things to be liberated fromthe front of the passenger cylinder head was the alternator and mountingbracket. As you can see, there are but three bolts that attach thecomplete assembly to the head. If your Mustang still has the Thermactorpump installed, there'll be two additional bolts to remove.
5. Remove the distributor cap and the plug wires from the engine. Usinga china marker or a dab of paint, mark the rotor location in relation tothe distributor housing, and then remove the distributor. As long as theengine is not rotated, you'll be able to drop the distributor back inand align the marks to start the car.