Mustang MonthlyHow To Engine
FE Big-Block Performance Solutions
Make the most of your classic Mustang 390/428 experience
Ford's venerable FE series big-block has been around since Dwight Eisenhower was president yet we just can't get enough of this tried and proven Ford big-block. The FE is the mill that won Le Mans three times beating Ferrari, so this engine is no one's kid brother. When the FE was introduced in 1958 in displacements of 332, 352, and 361ci, it wasn't considered a big-block because there were no small-block Fords in those days.
The FE had great architecture from the start with its skirted block and cylinder heads with great growth potential. And honestly, as Ford buffs, we're really not interested in the low-displacement FE engines of the “Leave It To Beaver” era, only the big gulps displacing 390, 427, and 428ci. These are the FE engines you can do a lot with given displacement and good high-flow cylinder heads. And thanks to this engine's great legacy the aftermarket has embraced it with reproduction blocks, heads, and induction when good factory and period pieces are unavailable or too expensive.
The raw physics of the FE big-block are what make it a no brainer to sort out because it offers you choice, strength, and simplicity. There are three basic bore sizes to work with from the Mustang years—4.050-inches (361, 390 and 410ci), 4.130-inches (406ci and 428ci), and 4.230-inches (427ci). The most common, of course, will be 4.050- and 4.130-inches. You can take these bores out .030, .040 and .060-inch and you can stroke them for great torque production capacity—and this is how you take the FE over the top without anyone really knowing what's inside. Because the FE in its most basic form has great bones for street and weekend strip use, it makes an excellent platform. If you're building a 390 High Performance or 428 Cobra Jet V-8, you can go so much further using your Mustang's original block coupled with additional stroke. These engines need stroke along with better heads and induction to support deep breathing. Even if you're not in a position to add stroke to your FE, you can still warm it up with better heads, induction, and a hotter cam.
Where the '67-'69 Mustang 390 Hi-Po fell short to begin with was heads, induction, and camshaft. The 428 Cobra Jet, with all its stroke and larger bore, would have been more impressive against the Camaro and Firebird with better heads, intake, and a hotter cam. We make this statement based on what the 390, 406, and 427 were in the early 1960s. The '61-'62 390/406 Tri-Power in Ford's Galaxie was what the 390 should have been for '67 with an aggressive mechanical flat tappet cam and a trio of two-throat carburetors. Instead, the Mustang got little more than the Galaxie's grocery getter 390 with so-called GT heads and a Holley 4150 carburetor. It needed more to compete successfully with the onslaught of ponycar competition that year.
Seeking Out Correct Blocks
Original standard bore or .030-inch oversize bore FE blocks are becoming harder to find as the supply of available cores dries up. If you're seeking a matching number (date code/casting number) block the challenge becomes even greater. For those building and restoring classic big-block '67-'69 Mustangs, finding just the right FE block for your application can take time. There are more 390 blocks out there than there are 428 Cobra Jet for obvious reasons. And if you find the right 390 or 428 Cobra Jet block, chances are it has been apart with at least one overbore. Because most 390s and all 428s have thicker cylinder walls than small-blocks, they can be bored to .060-inch oversize without consequence. However, all FE's exhibit some degree of core shift, so to be safe, cylinder walls should be sonic checked before any cleanup and machine work occurs. It is suggested you have the block Magnafluxed for cracks and other casting imperfections at the same time prior to the expense of any machine work. If you find a block bored to its limits, you can have it sleeved for around $800 to $1,000 and have a good block ready for action.
Because you're probably looking for '67-'70 390 or 428 block castings, this narrows the search down considerably. The 428 and 428CJ blocks may have come with a number of different casting numbers, or even no number at all. However, 98 percent of all true 428 blocks were marked with either a large “A” or “C” hand scratched into the rear face of the block mold at the foundry. It will appear as a raised letter, and the “C” can often resemble a lazy “J”. The majority of “A” blocks were cast with the standard duty main webs, while all the “C” blocks were cast with the heavy duty reinforced main webs. The 428 blocks are cast with larger cylinder bore cores than the 390 block. Over the years, many a 390 has been bored .080-inches to the standard 4.130-inch 428 size. Most of them have run hot or cracked with hard use.
Although a wide variety of factory iron head castings exist for FE engines, in truth there isn't much difference between them. Most FE heads have 2.04/1.55-inch intake/exhaust valve sizes with slight variations in port and chamber size. The 428 Cobra Jet cylinder head, as one example, is virtually identical to the 427 Low Riser casting—and this is what Bob Tasca plucked off the shelf when he was developing the KR-8 (Cobra Jet) for his own Mustang in 1967. The 428 Cobra Jet was born from off-the-shelf 427 parts mostly coupled with the torque advantage that comes from the 428's increased stroke. Tasca saw the advantage in the 428's stroke topped with 427 Low Riser heads (2.09/1.66-inch intake/exhaust), a hot hydraulic flat tappet cam, and the 428 Police Interceptor intake manifold. The Cobra Jet was born to make lots of torque, which made it perfect for drag racing.
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Before you are the three basic FE cylinder head types explained by author George Reid. From the bottom up are the 427 High Riser, Medium Riser, and Low Riser. The 428 Cobra Jet cylinder head is on par with the 427 Low Riser. A better head is the 427 Medium Riser; which is a great compromise between Low Riser and High Riser. The High Riser is a racing cylinder head not suitable for street use.
New FE Blocks
When we received the call from Bear Block Motors (BBM) announcing the arrival of its new reproduction 427 cross-bolt side-oiler blocks, it was like an answer from heaven. We anticipated another high dollar all-aluminum FE block few could afford, but that's not what we saw. Imagine an all-new 427 cross-bolted, side-oiler iron or aluminum block with casting and machining quality way beyond anything Ford did in the 1960s. This is not marketing hype, but cold hard iron or aluminum virtually identical to what Ford was producing back in the day.
What makes the new 427 block better is vastly improved technology and a high-standard casting technique for starters. The BBM FE 427 block is cast with high tensile diesel grade iron with a super thick .750-inch deck. Siamese cylinder walls allow you to bore to 4.440-inches. Out of the box, bores are 4.245-inches, to be finish honed to 4.250-inches. An optional 4.150-inch bore will be available for the 428 crowd. Cross-bolted main caps are a perfect interference fit amid the block skirts without spacers. Locating dowels in the main saddles “lock” the forged and heat-treated 8620 steel main caps in place.
Down under are heavier, thicker main webs and pan rails for superior strength. What's more, these redesigned FE blocks accept both FE and Cleveland main bearings, which gives you a wider choice of performance bearings. Water jackets are cast solid, right up to the bottom of lower core plugs, to maximize cylinder strength and support. You may use standard ARP FE head bolts or studs. Main oil gallery passages are larger than the factory originals for increased oil volume. These BBM FE iron blocks tip the scales at 250 pounds. Prices have not yet been announced.
New FE Aluminum Block
BBM is producing an FE aluminum block for just $1,200 more than the iron that weighs just 125 pounds. Made from virgin high-density aluminum using the best casting technique in the world, the BBM aluminum 427 is a dry sleeve block, and sports centrifugally spun, high tensile strength, nodular iron flanged sleeves. Maximum bore is 4.320-inches, with decks finished to 10.155-inches. All this block needs is finish honing and you are good to go.
The 428 Cobra Jet cylinder head, as one example, is virtually identical to the 427 Low Riser casting—and this is what Bob Tasca plucked off the shelf when he was developing the KR-8 (Cobra Jet) for his own Mustang in 1967.
Cylinder Head Duo From BBM
Bear Block Motors introduces its new FE aluminum cylinder head for 390, 427, and 428 big-blocks with 2.150/1.680-inch intake/exhaust valves with lightweight 11⁄32-inch stems. Combustion chambers are engineered for optimum swirl and quench right out of the box. Intake ports offer 295-plus cfm. Exhaust ports yield 225-plus cfm of flow. High-swirl/high-quench chambers allow for more aggressive ignition timing on today's more unforgiving pump gas. Also available are CNC-ported FE aluminum heads with 2.25/1.71-inch valves, which calls for 4.230-inch minimum bore size. Expect to see 355-plus cfm intake and 250-plus cfm from these CNC-ported pieces.
Blue Oval Performance Engineering