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.