How to Choose a Ford FE Engine Block

This chapter focuses on the foundation element of an FE Ford engine build—the block itself. The FE engine was in continuous production for roughly 20 years, so there are a lot of engine blocks   in  cars, garages, and junkyards. As the popularity of the FE engine has re-emerged, it seems that every one of these has magically become a 428 Cobra Jet, a Shelby part, or a “survivor” of some sort, even if they started out powering an F-150. While the focus of this book is performance building and not “numbers matching,” a certain amount of detective work is mandated when embarking upon any FE engine project.

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Here’s an average FE block; this is the way you find them when searching junkyards and classified ads. Before sinking a lot of money into rebuilding a block, you should Magnaflux the block to check for cracks and have it sonically tested to determine the thickness of the bores. Once you have selected a structurally sound block, the rebuilding process can begin.

 

FE Block Architecture
All FE engine blocks share many common design features, which serve to separate them from the other Ford V-8 engine families:

• 10-bolt cylinder-head pattern using 1/2-inch fasteners
• 10.17-inch deck height as measured from the crankshaft centerline to the cylinder head mounting surface
• 4.630-inch cylinder bore spacing
• Deep-skirt “Y”-block design where the oil pan rail completely encases the crankshaft and mainbearings
• Unique bellhousing pattern that isn’t shared with any other Ford engine
• A 2-bolt motor-mount pattern for pre-1965 blocks
• A 4-bolt mount pattern for later blocks, which can be retro-fit into earlier applications

The Blocks: Identification and Application

Ford FE engine blocks used for performance builds are generally selected from one of three groupings: 390, 428, and 427. While other blocks are out there, these three are the foundation for the vast majority of high-performance street and track applications.

 

The common singleweb- style block is found in most 360 and 390 engines. The vast majority of FE engine blocks have the straight two-bolt main bearing caps. However, the 427 engine had cross-bolted main bearing caps for greater strength.

 

Another view of the block shows the single main web reinforcement in detail. The thick main webs and deep skirt design provide excellent strength and help make the FE a very durable engine. It’s interesting to note that the latest GM LS series and Ford modular series engines share this block skirt configuration, as well as having the cross-bolted mains pioneered by the 427 FE.

 

390 Blocks

The 390-based blocks, which have an original bore diameter of 4.050 inches, are by far the most plentiful. These were in production from the late 1950s through the middle 1970s, with the majority being  used in large passenger cars and pickup trucks. The common 360 engine also utilized the 390 block, with no difference in features or markings, as did the 1966 410 Mercury. The blocks from medium-duty trucks are very similar to the 390 block, and are referred to as 361 or 391 engines. The medium-duty truck blocks have a larger distributor shaft hole, requiring a bushing for passenger- car use.

There are several differences in 390 engines from various years and applications. Perhaps the most obvious variance is the use of a double or reinforced main web design on the heavier-duty versions of the block. Most of the “mirror 105” blocks (see the casting information that follows), as well as the 361 and 391 medium-duty truck blocks carry this feature. It can also be found almost at random on other engines. If you have your choice, it’s probably the better piece, but the benefits are modest at best.

 

428 Blocks

The 428 blocks, used in numerous Galaxies, Thunderbirds, and high-performance Mustangs and Fairlanes, are far less common than the 390. These blocks are the basis for the famed 428 Cobra Jet engine and use a 4.130 basic bore dimension. Many 428 engines were also used as industrial and irrigation power plants. The Cobra Jet and industrial blocks usually have the double main webbing.

 

427 Blocks

The rarest and most desirable of the FE blocks is the revered 427—with either center oiler or side oiler. With a base bore diameter of 4.233, this was the basis for the engines found in cars such as the Thunderbolt or the NASCAR program. Most–but not all–427s have screw-in-type core plugs, a feature not found on any other FE engine.With very few exceptions, 427 blocks have cross-bolted main bearing caps, using 3/8-inch fasteners through the sides of the block to add significant strength to the FE bottom end. The center-oiler design uses the same lubrication strategy as that employed in more common FE engines, while the side-oiler design has a unique main-feed galley along the side of the block (hence the name). Side oilers can be said to prioritize main and rod oiling, with upper-end lubrication being transferred through grooved camshaft journals (more on this later).

 

The standard single web provides essential support for the main bearings and crankshaft. Also visible is the annular oil grooves in the cam bearing bore. This groove feeds oil to the rocker assembly. The groove can be added to side-oiler blocks to permit use of less expensive and more readily available cam bearings.

 

Most 427 blocks were used in high-performance passenger cars and were never produced in large volumes. Many others can be found in marine applications, but rarely in industrial engines. Brass-core plugs usually identify a 427 as a marine engine. Earlier 427 engines were all equipped with solid lifters, and have no provisions for lifter oiling; conversion for hydraulics is possible, but difficult and expensive. Many of the service blocks, the few used in the 1968 Cougar GTE, and the marine blocks usually have hydraulic-lifter oiling provisions. In addition, many marine 427s are cast as side oilers but drilled as center oilers.

 

The 428 block bottom is visually no different than a 360 or 390. You cannot go by appearance alone when trying to identify an FE block. The vast majority of blocks produced were used in trucks and started life as 360s or 390s; the 428 is a pretty rare part in comparison.

 

Passenger, service, or industrial 428 blocks often share a common external appearance. Many service blocks have vertical ribs on the exterior, and while these ribs do not add any appreciable strength, they likely make for a nicer pour during the casting process.

 

The casting numbers as shown on this 428 are useful for date code, but do not tell you what the engine actually is. Casting numbers on FE blocks are most often useful for exclusion, not for identification. As an example, a block with a 1964 date code cannot be a 428 because the 428 did not come out until 1966. Some FE blocks had a partial VIN (vehicle identification number) very lightly stamped into them, but even this is not a hard-and-fast rule. An FE hunt is going to require a dial caliper, a flashlight, and some patience.

 

A 428 block and a complete stroker rotating assembly are shown. No grinding or block clearancing is required to install a 4.25 stroke into an average FE. The stroker kits take a normal 390 up to approximately 445 ci, a 428 gets to 462, and a 427 reaches 482 cubes. At Survival we generally use a Scat cast crankshaft in most of the builds, which has proven to handle more than 750 hp with no issues. Diamond or Probe pistons, Scat 6.700-inch-long rods, race bearings, and plasma-moly rings that are file fitted are included in the rotating package. The 390-based engines almost always exceed 500 ft-lbs of torque with power between 450 and 500 with pump-gas-friendly compression of under 10:1. The bigger 427-based combinations have gone over 700 hp.

 

External Identification: How Can You Tell What You’ve Got? 

The short answer to this most frequently asked question is: You can’t, at least not from the outside of an assembled engine in the car. All FE engine-block castings appear nearly identical, with the notable exception of the side-oiler passages and cross bolts above/along the oil pan rail on many of the 427s. It takes a highly trained eye to notice the small cues that define a high-value part from the mundane. And even the best parts scrounger often cannot make a positive identification from markings alone on an assembled engine.

 

The “427” cast into the lifter valley it looks cool, but it means little in terms of block identification.

 

A 427 marine block showing a sideoiler casting has been machined flat for motor-mount clearance. The block is actually a hydraulic-lifter centeroiler design. Conversion to a side oiler by drilling is often impossible due to the machining.

 

The factory 427 main web is shown in detail. You need to carefully make note of the engraved markings on the spacers and their location because each spacer belongs in a particular location. They should have about a .001-inch press fit and can be fabricated if missing. However, line honing the mains will be required afterward.

 

Casting Marks

A good place to start your identification search, and a way to eliminate certain possibilities, is with the casting marks on the block. FE engine blocks usually have several casting numbers, both formal and sand scratches, on various areas of the block. Some of these marks are good for identification, but unfortunately many other markings were used almost at random and have little if any meaning for actual identification. I’ll cover the most common ones below, but remember that nothing on an FE can be taken for granted. There are actual noncross- bolted 427 industrial engines as well as paper-thin 390s sold as standard-bore 428s online. Take nothing for granted.

 

 

A typical center-oiler engine showing the angled feeds for the lifter galleys, which can be restricted if desired. We used to block them off on solid-lifter engines, but do not do so anymore. Restricting the oil feeds raises oil pressure and serves to keep the lubrication volume focused on the crank’s rod and main bearings.

 

The factory 427 side-oiler block is incredibly strong and able to support substantial modification. The side oiler found its way into some of the greatest race cars and super cars of the day, including the GT 40 and Shelby Cobra 427. Here, you see the webbing from another angle, and it’s similar to the double-web FE blocks, except for the cross bolts.

 

Mirror 105: Just like it says: a backward mirror image number “105” casting mark commonly found on the driver-side front face of blocks cast at Ford’s MCC foundry starting somewhere in the early to mid 1970s. It’s usually, but not always, a later-model 390 block with the extra main webbing.

352: The 352 designation is found on the driver-side front face of many of the FE blocks cast at Ford’s Dearborn Iron Foundry (DIF) throughout the 1960s. This does not mean you have a 352 engine, or anything else for that matter. Most 390 and 428 engines, as well as many 427s, have this marking.

66-427: This one is often found on the inner valley above the lifters or on the bellhousing face. It tends to get folks really excited for a few minutes, but it means pretty much nothing. It’s often found on otherwise normal 390 engines.

C Scratch: This is a good one to find. Found as a freehand letter “C” scratched in the bellhousing area of the block, this is considered a good indicator of the double-webbed 428 CJ block.

 

A “352” casting in the bellhousing area does not mean that it’s a 352 engine. Instead, this is a common casting designator in the FE engines of the era. The 352 casting designation was often found on most 390 and 428 engines as well as many 427s. Also visible are staked oil galley plugs, which are a simple low-cost alternative to screw-in conversion.

 

A Scratch: Another one that’s nice to find. This is the letter “A” freehand scratched into the bellhousing area casting and normally associated with non-CJ 428 engines.

Inside the Water Jackets: Proof positive of a 428. If you remove the center freeze plug, you can often see the number “428” cast right into the base of the water-jacket core. You can also find similar casting identification by looking straight down through the water opening on the decks where the head gaskets go— you’ll need a flashlight.

Casting Numbers, such as C6MAxx: These numbers are normally found cast upside down below the oil-filter-mounting pad. Unfortunately, they don’t really mean all that much. While important for a restoration project, the fact is that Ford used the same casting number across a wide variety of engine sizes and levels. That means that these numbers do not help for identification other than for exclusion. You know that a D4TE (the “D4” indicates 1974 in Ford code) is not going to be a 352, which was discontinued in 1966.

 

Front of a common FE block showing the “352” casting mark. All FE blocks have bore spacing of 4.63 inches, a deck height of 10.17 inches, and a main journal diameter of 2.749 inches.

 

The “428” designation is cast in the base of the water jacket as seen through the cylinder head deck-cooling opening. Similar casting numbers are also often found below the center freeze plug. This is a true indicator of the block’s 428 casting core.

 

Date Codes: Often, but not always, cast in place alongside the casting number, the date codes tell you when the block was made. Like the casting number, these do not tell you anything about the engine itself other than by exclusion; i.e., a block cast in 1964 is not a Cobra Jet since those started in 1968. Date codes are the “holy grail” for restoration work, but they have limited value for performance efforts.

Cross Bolts: It’s most likely a 427, unless a racer or hot rodder has added them sometime in the block’s history.

 

You’re looking at the 428 rear surface. Most 428 blocks have a handscratched “A” or “C” in the bellhousing part of the casting. The “A” is generally considered to be a passenger-car 428, while a “C” is a Cobra Jet. There are no scratch marks on this one, but it is a 428!

 

A “66-427” cast in the bellhousing can be exciting to see, but is often found on otherwise-common 390 engines. Ford used the casting molds on everything with regard to the actual engine block being cast.

 

Some scratches were done by hand as an identification method in the foundry, and often look “backward” or crudely formed. They sometimes can provide a means of identification although many marks were randomly used and don’t provide any actual ID information. A “C” scratch on back of a 428 is considered a good indication of a Cobra Jet block, when combined with date codes in the 1969–1970 timeframe.

 

The “A” scratch is often found in the bellhousing area on a passenger 428 block. The actual meaning of the letter A is unknown, but it usually appears only on passengercar 428 blocks.

 

Windows in the block! This is an unfortunate but common finding. The rod broke and destroyed the block. A stock rotating assembling can usually handle plenty of horsepower, but the rods are prone to failure after years of hard service. They break in the thin area about 2 inches below the pin. Often, windowed 427 blocks can be repaired and raced again, but this one is broken through the cross-bolt boss, so it is best relegated to street use only now.

 

Screw-in core plugs: Most often indicates a 427, unless a racer or hot rodder has added them sometime in the block’s history.

 

The “Drill Bit Test”

This one test is the single best way to quickly identify an assembled FE block, and credit for it goes to FordFE.com forum member David “Shoe” Schouweiler. You only need the simplest of measuring tools– some drill bits. The following is paraphrased from several of Dave’s responses to block identification questions posed on the forum.

Remove the center freeze plug from the side of the engine block. Using common drill bits, then slip the shank portion of the largest possible bit in between the center cylinder cores through the freeze plug opening. The size of this largest drill bit indicates which water-jacket core was used to cast the block.

If you can only fit a 1/8- or 9/64- inch drill bit shank between the cylinders at the largest gap position on the block, and a 10/64-inch bit doesn’t fit anywhere, then they are 427 water jackets.

406/428/DIF361/DIF391 blocks allow a 13/64-inch drill bit shankto fit into the gap at the largest position.

MCC361FT/MCC391FT blocks (MCC = “mirror 105” marking) allow a 14/64-inch bit to fit between the cores.

Regular 360/390/410 blocks hang around the 17/64- to 19/64-inch water-jacket space at the largest position on the block.

These are only approximations, but tend to be close.

Even if you do have the good jackets, be sure to sonic map the cylinders before boring. If the core has shifted, it could cause problems. It is not at all unusual for FE engines to have considerable core shift. And the oft-raced and abused 427 engines seem to have some of the thinnest cylinders. A block with core shift has cylinders that are thicker on one side and thinner on the other. This can leave the cylinder wall too thin after machining, compromising strength and piston-ring seal.

 

The New Blocks: Aftermarket Offerings

The FE engine’s recent renaissance has fostered considerable interest from the automotive racing aftermarket. Among the new FE parts now available are several brand-new engine blocks from, in no particular order, Dove, Genesis, Pond, and Shelby.

Most of my personal experience has been with the Genesis and Pond offerings. Thus, they are covered here in detail. Any of these blocks are considerably stronger than any factory parts.

 

The Genesis, Pond, and OE blocks are rarely found in one location. Having them all in one place makes for some interesting comparisons. Both Genesis and Pond are continuously improving their products, so those shown here will not likely be identical to the one you purchase.

 

Several FE blocks were used for the comparisons in this chapter. Included in this picture are Genesis blocks in both iron (black; upper left) and aluminum (back row), Pond aluminum blocks (front row), and a factory 427 in blue (right center).

 

The factory 427 engines can be identified by their unique crossbolted main caps, which have small spacers. These spacers are unique to their position and reside between the oil pan rail and the cap. The aftermarket block suppliers have taken this a step further by integrating the spacers into the main caps themselves. On the Genesis blocks, the spacers have a protruding flat section that looks like a “T.” Pond blocks extend the entire cap to the side of the pan rail and have a larger flat register alongside the main bearing bore. Pond also adds a dowel pin for positive cap location.

The Genesis iron block has siamesed cylinders; they join together rather than having water flow between them. This allows a bore diameter far larger than any factory FE. At Survival Motorsports, we’ve over bored 4.375 inches frequently, compared to the original equipment (OE) parts, which become marginal at anything beyond 4.270 to 4.280 inches. The Genesis and Pond aluminum blocks use pressed-in-place cylinder liners and are good to roughly 4.310-inch bore diameters. Any build targeting serious high horsepower would be well served by starting with an aftermarket block.

The Genesis block looks virtually identical to a factory 427 on the outside, with the same screw-in core plugs and casting contours. Even a sharp eye cannot tell this from an original. The Pond block looks very similar with minor changes—larger cooling passages make for a smoother exterior, and the use of CNC O-ring sealed plugs tell the knowledgeable observer that this is not a stock piece.

Written by Barry Robotnik and Republished with Permission of CarTech Inc