KJ Jones Senior Technical Editor
August 1, 2008
Photos By: Hannah Montoya, Greg Montoya
Dart Machinery's new Iron Eagle cylinder heads highlight Greg Montoya's H/C/I swap. The cast-iron heads (PN 13301182; $1,053.95) feature beautifully radiused, 1.175-inch wide x 2.050-inch tall, 180cc intake ports that flow 247 cfm at 0.500-inch lift.

Horse Sense: A 5.0 H/C/I swap really isn't an overwhelming ordeal for the average mechanically adept enthusiast who has a good understanding of how to take parts off and put them back on. As it is with anything else that involves working with an engine, the number-one rule of thumb to follow is: Take your time. For great step-by-step details on the H/C/I-swap procedures themselves, grab a Haynes Automotive Repair manual for Ford engines (www.haynes.com). It's thorough, it has pictures, and it's exactly what you need for clearing up any confusion you have about the job.

Keeping track of all the high-flowing cylinder heads, high-revving camshafts, and high-performance cold-air systems available for Two-, Three-, and Four-Valve 'Stangs is no easy task in our predominately modular world. Manufacturers are constantly offering us new technology for 4.6-powered Mustangs, so you can imagine how excited OG 'Stangbangers like your tech editor and Editor Steve Turner get when we hear about anything new for good ol' 5.0-liter engines-the bullets that helped lay the groundwork for the Mustang madness we all thrive on today.

Not bad, for DIY. That's right: This is the stock 5.0 that was nestled between the front fenders of Greg's 'Stang at the outset of our project. Greg built this engine himself after scoring the car as a roller in a multilevel trade deal that rivals that of professional athletes. We're still trying to figure out the details, but based on the appearance of the clean, white '89 GT, the car will be a cool street cruiser, and hopefully a Pony that will hold its own on the track as well.

Dart Machinery is recognized by Mustang racers and enthusiasts as the maker of the Iron Eagle series of 302 and 351W engine blocks. The company is better known for its blocks than for producing small-block Ford cylinder heads way back in 'Stangbanging's early years.

That's right: cylinder heads-and cast-iron cylinder heads, at that. Dart's Windsor and Windsor Junior heads were among the limited number of must-have Fox Mustang performance parts back in the day. The 5.0 in your tech editor's nitrous-injected '84 GT sported a pair of Juniors that helped carry the street/strip 'Stang to 10-second e.t.'s in the mid '90s.

The heads' composition made them much heavier than the all-hallowed aluminum heads that have ruled the 5.0 roost since the mid-to-late '90s. Despite that, high-volume ports, larger valves, and combustion chamber improvements (over Ford's E7TEs) enabled Dart's heads to flow a lot of air. When combined with camshafts and intake manifolds that complement their capabilities, they sent many street- and drag-race 'Stangs into the low-e.t. zone for a relatively small monetary and time investment.

Fast-forward to today, and Dart is once again giving us a good reason to be interested in its cylinder heads. No, there hasn't been any improvement in its Pro-1 CNC aluminum heads. What we're amped about are Dart's new cast-iron heads, which-similar to its popular blocks-are also called Iron Eagle.

Marking the rotor's position at top dead center is an important disassembly procedure when you're swapping camshafts and intake manifolds. The distributor must be removed unless you're only changing the intake manifold. Making this reference ensures the distributor is reinstalled at the same position in the timing sequence, and the engine should fire right up.

Once again we're exploring the performance capabilities of heads/cam/intake combinations for 5.0 Mustangs. However, unlike other reports we've done on this topic that feature H/C/I packages offered by manufacturers, we've compiled pieces from individual companies we think make up a compatible, affordable package that will do well on a stock Fox Mustang engine.

The Iron Eagles are flying at the front of this effort, along with a street/strip N-41 hydraulic-roller camshaft from Anderson Ford Motorsport and high-flowing intake components (SSI Series manifold, 70mm throttle body, and a cold-air induction system) from BBK Performance.

We know your thirst lies in how much power the assortment makes, so we won't dawdle too much on the installation of this bolt-on package. The accompanying photos and captions illustrate highlights and notes on the install from our buddy Greg Montoya, a do-it-yourself 'Stangbanger who was ready to take the bone-stock powerplant (save for short-tube headers) in his '89 Mustang GT to a budget-friendly but better level of performance.

Greg handled the parts swapping in a few evenings at his home garage after work. As you'll see when you read further, the H/C/I package we selected proved to be well worth his time and the impressively small monetary investments.

Once all of the necessary disconnections are made, Greg lifts the lower intake manifold from the block. The stock fuel rails and 19-lb/hr injectors can remain in place during this step. They'll be replaced with BBK's big fuel rails and 24-lb/hr injectors, which Greg won in an eBay auction.

Pulling the stock heads requires some muscle, as will lowering Dart's new iron heads. Greg actually used heads from an '87 302 (E7) for his rebuild. At 1.05 inches wide x 1.90 inches tall, the intake ports on the stock heads are considerably smaller than those on the heads being used for our upgrade.

As H/C/I swaps go, we've evaluated combinations sold in package form that average $3,000. For this project, we selected Dart's Iron Eagle cylinder heads; a BBK Performance fuel-pressure regulator (PN 1706; $99.95), cold-air kit (PN 1557; $165.95), and a single-stage intake manifold system that includes a 70mm throttle body and fuel rails (PN 5002; $559.95); and Anderson Ford Motorsports' N-41 camshaft (PN AF-N41; $299.00). Not shown are Harland Sharp's new Diamond Series 1.6 ratio, 7/16-inch, stud-mount roller rocker arms (PN SD4003-7; $365.00) and the ARP 3/8- to 1/2-inch stepped head bolts (PN 254-3708; $177.16) required for installing the Iron Eagles.

Using a little Royal Purple Max Tuff as a prelube, the new camshaft is stabbed in place. The prelube isn't a requirement with a hydraulic-roller camshaft, but it makes Greg comfortable.

Since the 302 short-block has only 220 miles since its rebuild, the double-roller timing chain and hydraulic-roller lifters are reused for this cam swap.

This is a close look at the 58cc combustion chamber of Dart's new Iron Eagle cylinder heads. The heads feature 1.94 (intake)/1.60 (exhaust) stainless steel valves, which are totally compliant with the engine's stock pistons and the new Anderson camshaft. The valves are also available with 2.02 intake valves. Dart flat-mills its Iron Eagles 0.006 inch per cubic centimeter, and it angle mills the heads 0.0075 inch per cubic centimeter.

Iron Eagles' exhaust ports also blow away those of stock 5.0 heads. These ports measure 1.325 inches wide x 1.350 inches tall, flowing 159 cfm at 0.500 lift. We dig the standard exhaust bolt pattern, which allows Greg to stay with short-tubes or eventually bolt up any standard long-tube Fox-body headers he desires.

Stock head bolts can't be used to install Dart's Iron Eagle cylinder heads on a standard 8.2-deck block because they require a 1/2-inch bolt.

ARP's stepped head-bolt kit is called into action and Greg torques each fastener with 75 lb-ft of torque.

After installing the 7/16-inch studs included with the Iron Eagles, Greg topped off the new heads with 16 of Harland Sharp's Diamond Series roller rockers. Per the AFM cam card, we're staying with a 1.6 ratio for the rockers, and as usual with a hydraulic-roller cam, lash is adjusted to zero. The 1.437-inch double springs and steel retainers on the heads are included, but the stock pushrods are reused with this setup.

Before positioning the BBK SSI Series intake on the engine, its lower intake must be pre-assembled with the high-flow fuel rails, regulator, crossover tube, and all of the various EEC sensors. This lower manifold features long equal-length runners that deposit air/fuel into a huge, open plenum area. Based on the intake's overall design, we think it should work well with the heads and our selected camshaft.

BBK includes two O-rings for the fuel crossover tube. However, due to the tube's location below the upper manifold and the difficulty Greg will have trying to access the tube once the upper is installed, he adds two additional O-rings (one on each side) for added insurance against a possible leak.

The engine's original vacuum T must be transferred to the boss in the SSI upper intake.

Before lowering the upper manifold, the main engine harness and other wiring must be zip-tied and moved completely out of the way. The SSI upper is a lot bulkier than a stock 5.0's, so the more clearance you have when installing it, the better.

With the lower manifold down, Greg installs the radical dual-plenum SSI upper intake. In addition to its wild appearance, the 75mm throttle-body opening and built-in EGR spacer are a couple of the other features on this intake that we think are cool. Notice the OEM valve covers are in place. The stock valve-cover bolts are too long for the Iron Eagle heads, so a shim is added to each bolt to make up the clearance difference and nix the possibility of experiencing a major oil leak. The throttle cable, PCV valve, vacuum hoses, and sensors are also reconnected once the upper intake is installed.

This plenum-cover gasket must be slipped in place before the cover is installed. Greg says mounting screws for the plate must be tightened evenly in a crisscross pattern to avoid a vacuum leak.

Since the factory thermostat housing on Greg's 5.0 had seen better days, we decided to upgrade with this clean 15-degree piece (PN 1066) from Performance Stainless Steel. The housing is made from CNC-machined 304 stainless and snugs up to the new manifold with the included Cometic gasket.

A fenderwell-mounted BBK cold-air system rounds out the upgrade components we're using on Greg's Pony. The high-flow conical air filter is in the fender, and air is channeled up through an 80mm C&L mass air housing that features a sampling tube sized for 24-lb/hr fuel injectors.

We reconvened back at Extreme Automotive shortly after Greg completed his H/C/I project. Our baseline numbers already had been recorded and stored in the dyno's computer. Saul "The Surgeon" Gutierrez is the resident dyno master and tuner at Extreme. After a quick timing (15 degrees advanced) and fuel pressure (32 psi) check, it's time to see how the parts perform.

Summit Racing's off-road X-shape crossover is a last-minute addition to our upgrade. The pipe arrived one day before our dyno appointment, so we bolted it on before making any pulls and gave the stock catalytics a well-earned rest.

Here's proof that the H/C/I setup we came up with is no joke. Lead by Dart's Iron Eagle cast-iron cylinder heads and a supporting cast that includes an N-41 cam and intake/air-induction goodies from BBK Performance, Greg Montoya's pumped-up Pony gained a smooth 103 rwhp (peak to peak) with an additional 45 lb-ft of torque.

Greg's 'Stang is naturally aspirated, so we're fairly sure there's plenty of room for additional stout gains if a blower, turbo, or nitrous are added. A swap to Anderson's B-41 S/C cam, gears, bigger injectors, and a 90mm mass air will be necessary as well.

Besides the small total investment for the parts and the fact that this setup can be installed at home, the coolness is brought on by the fact that everything is compatible enough for the combination to make great power. On a stock-5.0 short-block, without any radical tuning other than setting timing and fuel pressure (no chips), we think the Dart/AFM/BBK H/C/I setup is a collection to consider for a stock-Fox performance upgrade.