RESTORING A 1967 SHELBY G.T. 500'S 428 POLICE INTERCEPTOR ENGINE

By the year 1967, the domestic horsepower race was shifting into overdrive. Ford and Carroll Shelby were enjoying the afterglow of winning Le Mans with the big-block GT40 in 1966. This was also the year that Ford redesigned the Mustang into a larger and heavier body style. But the 390 GT was disappointing from a performance standpoint so Shelby quickly decided to stuff the new 428 Police Interceptor (P.I.) engine into the GT500 Shelby Mustang.

The induction system is what sets the 1967 Shelby 428 apart from its more casual 428 contemporaries. These are original 600 cfm Ford / Holley vacuum secondary carburetors. It may not be immediately noticeable that Ford elected to mount the carburetors backwards and actuate them using a rather complex progressive linkage system fitted with a hefty throttle return spring. Photo: Jeff Lilly Restorations

But because Shelby was an innovator and a hot rodder, a single four-barrel version would have been pedestrian and hardly in keeping with his company image. So he opted instead to bolt on a bit more visual and performance appeal by topping the 428 P.I. engine with a Ford 427 Medium Riser 2x4-barrel intake manifold and a pair of 650 cfm Holley carburetors. While 1,300 cfm was clearly a bit of airflow overkill, it was not an unusual approach to performance in those days. Exhaust emissions and fuel mileage be damned – it was full speed ahead.

Each carburetor features its original metal tag. Since these are vacuum secondary carburetors, each carb uses a separate vacuum line routed to the intake manifold. Any kind of primary or secondary jetting change would require removing one of the carburetors to complete the task. The horizontal white tube is woven asbestos insulation for the choke heat source line originating in the passenger side exhaust manifold.Photo: Jeff Lilly Restorations

The engine in these amazing images from Jeff Lilly Restorations is nothing less than an homage to the time when Ford was topping everyone with its Total Performance approach to selling cars. Shelby merely dumped gasoline on the fire with his 428 and was reaping the rewards. This particular engine was under-rated at a mere 355 horsepower at 5,400 rpm.

To ensure the correct carburetors, the first place to look is on the choke housing for the factory part number C3AF-9310. This indicates these carbs were originally used on 1963 (C3) 427 engines, which was indeed the case for the Shelby 428 engine. The 2804 and 2805 List specify this application. The date code of 715 indicates the first carb was built in 1967, in January in the 5th week. Photo: Jeff Lilly Restorations

The 721 on the second carb reveals a 1967, February, 1st week manufacture.Photo: Jeff Lilly Restorations

As with nearly all Ford engines of that era, this version is festooned with interesting little factory small parts that for the restoration artist are where all the Easter eggs can be found. We’ll start with some basic specs and then work our way through this engine top to bottom much like a tour guide through the hallways of a Ford 428 Shelby Cobra Jet engine museum.

The casting number C7ZX-9425-A reveals the intake as a Medium Riser 427 twin four-barrel version with a 1967 casting date which is the correct intake for this Shelby 428 P.I. Photo: Jeff Lilly Restorations

The 428 was Ford’s production answer to the demand for a 7 liter big-block that would be less expensive to build than the FE 427 that preceded it. The 428 was the largest within the FE family bloodline that started in the late ‘50s with the diminutive 332ci truck engine. The 428 continued to use the FE’s Y-block configuration but sported a 0.100-inch smaller bore but enhanced with a much longer stroke than its 427 cousin. The 428 Police Interceptor engine featured 10.5:1 compression and a mild hydraulic flat tappet camshaft. The block was also configured to support hydraulic lifters with oil directed to the lifters first and sported a nodular iron crankshaft and two-bolt main caps.

These reproduction Autolite suppression radio resistance wires are also marked with individual cylinder numbers and feature the classic orange Autolite spark plug boots. . Photo: Jeff Lilly Restorations

Many consider the 428 as merely a bored and stroked 390. The camshaft was essentially a 390 GT Mustang hydraulic flat tappet grind combined with a set of Medium Riser cylinder heads that are also similar to the 390 GT castings from that year. But it sounds more exotic if you state that these are Shelby GT 500 castings.

All Shelby 428 engines came with power steering and the required pump assembly which has been carefully restored. Photo: Jeff Lilly Restorations

Shelby used this engine mainly because it was the newest addition to the Ford line while the more race-oriented 427 was being phased out. But what the 428 P.I. may have lacked in bold construction, it made up for with an impressive induction sporting the 427 Medium Riser dual four-barrel aluminum intake and twin 600 cfm carburetors. Adding to the engine’s panache was a giant oval air cleaner and finned aluminum valve covers that connect you with Le Mans through bold cast letters.

This is a factory engine lift flange bolted to the exhaust manifold side of the head. You can also see the C7AE-A cylinder head casting mark next to head bolt.Photo: Jeff Lilly Restorations

Yank the air cleaner and you are faced with a pair of 600 cfm Holley 4160 carburetors. We could spend the rest of this story just on all the tiny details that make these carburetors singular. Let’s start with the interesting reversed fore-aft orientation. The throttle linkage is on the passenger side, requiring a linkage arrangement that pulls a cross shaft through the middle of the intake manifold and ties into a progressive arrangement to make it all function normally.

Heated air for the choke is first drawn through this interesting inlet filter before it travels through a tunnel inside the passenger side exhaust manifold before being routed with an insulated tube to the carburetor choke. Photo: Jeff Lilly Restorations

Only the primary carburetor employs a choke arrangement that pulls heated air through the exhaust manifolds and into the choke housing. The line is insulated and originates with the passenger side exhaust manifold. The 600 cfm Holley carbs were originally employed on an earlier 1963 R-code 427 Galaxies and re-employed for the Shelby application with later date coding.

Imagine trying to find NOS oil and fuel filters for this nearly 60 year-old engine! Luckily, accurate reproduction filters are available through several outlets such as CJ Classic Mustangs, Scott Drake, and others. Photo: Jeff Lilly Restorations

If restoring one of these singular 428 dual quad engines is on your bucket list, there is a company we found during our research called AirFuelSpark (afscarburetors.com) that offers a few of the interesting and unique components used on these engines back in the day. The company also performs complete carburetor restoration for these ‘60s Fords carburetors.

Nearly all Ford FE blocks feature this 352 casting number. The earliest FE engine was a 332ci engine from the late ‘50s and eventually grew to the now familiar 352 / 360 / 390 / 406 / 420 / 427 / 428 family of engines.Photo: Jeff Lilly Restorations

Among this engine’s interesting features is the vacuum advance was intentionally blocked off with screw-in plugs into the primary metering blocks. Of further note are the primary and secondary bowl vents used on these carburetors to prevent rich mixture operation caused during low-speed driving where the fuel could percolate and enter the engine through the squared-off vent tubes located next to the venturis inside the air cleaner.

Not surprisingly, Ford also marked their engine-driven fan blades. For Ford restorers, this H C6OE-F stamping indicates an 18-inch fan assembly used on Mustangs as well as other applications. Photo: Jeff Lilly Restorations

But there’s still the rest of the engine to address which leads us next to the dual points distributor that is missing the vacuum advance canister. Looking back at the carburetors, you can see that specific plugs have been added to the Holleys to block off this normal vacuum advance port. This was all part of the plan.

This casting number C6ME-A is among the most common and can be traced through multiple FE engine combinations – including the 428 Police Interceptor engine. Photo: Jeff Lilly Restorations

The front accessory drive for this particular engine includes a dual belt drive for the water pump and alternator along with a single belt driving a FoMoCo power steering pump which was required on all Shelby applications along with power brakes. This was in keeping with Shelby’s direction to make these cars a bit more docile for the street as compared to the stripped-down GT 350’s of 1965 / 1966 that were pure racers at heart. This new GT500 would be more of a Grand Touring car approach. Some Shelby 500’s were fitted with air conditioning with the compressor mounted on the driver side front.

All Ford 428 engines were externally balanced and therefore required a specific balancer matched to the engine. The crank pulley is a casting rather than a stamped metal and carries the correct C1AE-63-12-A numbering. Also note the correct crank bolt and attaching hardware. Photo: Jeff Lilly Restorations

In keeping with this engine’s historical lineage, we don’t have to look far to discover that all the casting and part numbers are in keeping with its historical approach. Even the alternator is properly marked with the right orange color code to signify it as 15-volt, 42-amp charger. Looking closer, the distributor is one of Ford’s dual point versions common to many FE applications of the day along with reproduction suppression spark plug wires complete with individual cylinder numbering and those classic Autolite orange spark plug boots.

It’s the little details like this OE valve cover grommet that warms a Ford purist’s heart. Reproduction grommets are similar, but not exactly the same as this OE C7AE-6A892-A piece.Photo: Jeff Lilly Restorations

Diving into the details, the exhaust manifolds were production Mustang versions and not something unique to this first year Mustang with differing casting numbers for driver and passenger side manifolds. Since details make the difference, even the exhaust manifold bolts carry the proper head markings and date coded manifolds to reinforce its pedigree.

The exhaust manifolds are not unique to the Shelby 428. However, these restored versions do offer the correct casting numbers with this one, C6OE-9430 A, for the passenger side. Photo: Jeff Lilly Restorations

Since these are OE original manifolds, they didn’t always look this pristine. Lilly Restorations blasts the manifolds and then uses Seymour High Temp Cast Blast spray paint to bring the manifolds back to looking new. According to the manufacturer, the paint can withstand up to 1,200 degrees F temperatures.

Ford alternators came in several different output configurations. While externally similar, they were more easily identified by a factory stamp on the housing using various colors for the output differences. The orange stamp identifies the alternator as the 42-amp version. Photo: Jeff Lilly Restorations

The aftermarket has certainly assisted in this restoration endeavor that also includes reproducing the historic Autolite red and white oil and fuel filters, complete with the correct part numbers and tightening instructions. This is especially useful for Ford engines since both filters are prominently placed up front.

Clearly Jeff Lilly Restorations has hit another home run with this Shelby 428 FE engine and we expect the car will be just as magnificent reflected back against this restored powerplant.

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Jeff Lilly Restorations

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2023-12-24T16:14:20Z dg43tfdfdgfd