Ford’s venerable Modular engines have been a Ford mainstay for three decades. The 4.6L “Mod’ Motor” SOHC V8 first appeared in the 1991 Lincoln Town Car and quickly made its way across most Ford car and truck lines in the years to follow. Ford upped the performance agenda with a screaming 32 valve DOHC Modular in the Lincoln Mark VIII in 1993 and in the SVT Mustang Cobra in 1996.

It even installed this beast sideways in the front-drive Lincoln Continental sedan!

(Image/Jim Smart)

The term “Modular” has never been about the engine itself, but instead Ford’s approach to making quick production line changeovers from one type of Modular engine to another without losing precious time.

Although there has always been a lot of confusion regarding the Ford Modular engines, one basic fact remains consistent—they are darned confusing.

Understanding Ford Romeo & Windsor Modular Engines

We’re going to ease the confusion for you. Ford built the Modular engines in two plants—Romeo, Michigan (originally a Ford Tractor plant) and Windsor (Essex), Ontario, Canada. What’s more, because each Modular engine plant had its own approach to this engine’s architecture, it is challenging to determine which parts fit which engine.

Engineering differences and changes are commonplace at Ford, which makes us envious of the Chevy guys where ease of interchangeability has been a given across the decades. Very little has changed in the small block Chevy since its introduction in 1955. What’s more, Chevrolet is still making these timeless mills seven decades later.

Romeo and Windsor had different approaches to the Modular engines—making interchangeability challenging and frustrating. Some components interchange while others do not. For example, Romeo and Windsor 16-valve SOHC engines employ different cylinder heads, valve covers, timing covers, and valvetrains. There’s a wide variety of timing covers for different applications because these engines were factory installed in several vehicle types. Romeo engines use different timing components than Windsor engines. They are not interchangeable.

In fact, there are more differences in these engines than we have room to address here.

There are very significant differences in these engines you must be aware of or face unnecessary loss of time and a lot of expense. Best advice is to stick with Romeo heads on a Romeo block—and Windsor heads on a Windsor block to minimize wasted time and frustration. Do not be tempted to mix them up.

From 1991-96, there was one Modular engine plant—Romeo. With the introduction of the all-new Ford F-150 and F-250 trucks for 1997 came “truck-based” Modular engines from the Windsor engine plant displacing 4.6L, 5.4L (both V8s) and the 6.8L (V10). The 6.8L V10 replaced the time-proven 460ci big block V8.

Suffice it to say Windsor Modulars are truck engines by design although you will see Windsor engines at times in passenger cars—especially the Mustang GT in 1999 and 2000. Early 1997 F-150 trucks built in early in 1996 were fitted with 4.6L Romeo Modular engines.

Romeo Modulars have six-bolt cranks while Windsor engines have eight-bolt. This fact alone confirms the Windsor Modular’s status as a heavy-duty truck engine.

Building a High Performance Ford Modular V8

JGM Performance Engineering in Valencia, California decided to build this 5.3L SOHC Modular V8 from scratch using all new parts, including the Ford Performance M-6010-BOSS50 Windsor 5.0L block topped with Trick Flow Twisted Wedge Race 195 heads. They wanted a high-revving street/strip beast that would be civilized for the daily commute, yet ready for race action on a Saturday night.

Trick Flow Twisted Wedge Race 195 Series cylinder heads are the most optimum cylinder heads for the Ford Modulars thanks to such an innovative design that reinvents the “PI” (Performance Improved) Modular head. What makes them innovative is their combustion chambers and intake valves are relocated to the opposite side of the camshaft.

Other nice features include factory PI-shaped intake ports (making them compatible with all induction systems), runners that deliver CNC caliber porting along with CNC-profiled combustion chambers, 3/4 inch thick decks, patented replaceable cam bearing journals, and 3/4 inch reach spark plugs.

The Twisted Wedge Race 195 heads are engineered for Modular engines with nice power adders and/or high revving applications because these engines like to rev. These heads fit all SOHC Romeo and Windsor engines and will accept all OE-style camshafts, followers, lash adjusters, valve covers, and most factory Ford timing covers.

Because JGM wanted 500 horsepower, they looked to Trick Flow Specialties for answers.

What makes this Modular engine build exciting is the Trick Flow Twisted Wedge cylinder heads, camshaft, and valvetrain along with Edelbrock Victor Jr. single plane induction topped with Holley 750 cfm HP carburetion

Trick Flow Specialties (TFS) went back to the drawing board with the Modular head—reinventing its rather conservative 16-valve cylinder heads. It is remarkable just how different these poly-angle valve TFS heads are. The original Modular “Non-PI” heads flowed 175/150 cfm intake/exhaust at 0.600 inch lift. The 1999-up Performance Improved (PI) head flows 203/185 cfm intake/exhaust at 0.600 inch lift. JGM flow-benched the TFS Twisted Wedge heads and found 276/199 cfm at 0.600 inch right out of the box without port and bowl work—incredible flow numbers prior to any port work (which would push these flow numbers even higher). 

JGM originally intended to build a 5.3L Modular first with carburetion and a series of dyno tests—then, switch to the engine’s factory-engineered EFI induction system with port fuel injection and a variety of intake manifolds and throttle bodies.

Disappointment abounds when we tell you this engine has yet to make it to the dyno. JGM has been extraordinarily busy with dyno appointments, which has prohibited this engine from getting to their dyno room. As a result, we’re going to give you the recipe for a terrific 5.3L SOHC Modular and see how this formula works for you. When JGM gets this engine on the dyno, we will report the numbers to you. We’re always interested in your feedback and what your experiences have been with Ford’s time-proven Modular mill. How did you make power and what went into your build?

We’re working with the Ford Performance Parts M-6010-BOSS50 block. This is a beefy heavy-duty block that will handle the power expected. (Image/Jim Smart)
Because JGM wanted more displacement, it bored the block 0.148 inch oversize to work alongside an increase in stroke. (Image/Jim Smart)
Block was finish-honed to achieve a good crosshatch pattern for cylinder sealing and oil control. (Image/Jim Smart)
(Image/Jim Smart)
Because the Trick Flow Twisted Wedge Race 195 heads’ intake valves are relocated for improved flow, our JE custom forged pistons had to be fly cut for valve clearances. (Image/Jim Smart)
(Image/Jim Smart)
Pistons and cylinder walls have been bathed in assembly lube for a slippery wet start-up. (Image/Jim Smart)
JGM opted for Eagle H-beam rods and a steel stroker crank for maximum durability. (Image/Jim Smart)
The JGM/Trick Flow 5.3L Modular sports increases in bore and stroke from the 4.6L’s 3.552 inch (bore) and 3.543 inch (stroke) to the 5.3L’s 3.700/3.750 inch bore/stroke combo. This approach makes the most of the BOSS block. (Image/Jim Smart)
We like Eagle’s forged steel stroker crank, which adds 0.157 inch to the Modular’s 3.543 inch stroke to get 3.750 inches. Eagle does a really nice job for your hard-earned money. (Image/Jim Smart)
First order of business once the bottom end is assembled is to check for true top-dead-center. This is done with a dial indicator seated at the block deck above the piston. The crank is slowly turned both ways to either side of top-dead-center with needle movement confirmed. Once dead center of crank rotation is confirmed, you’ve found true top-dead-center. This step is a must before degreeing the cams. If true top-dead-center is not confirmed, nothing else is going to be right. (Image/Jim Smart)

Ford 500+ HP 5.3L Mod Motor COMP Camshaft Specs

Duration at 0.050" Valve Lift Lobe Separation Angle Valve Timing at 0.050"
Intake 2340.545"1127° BTDC (Open)
47° ABDC (Close)
Exhaust 2340.545"11251° BTDC (Open)
3° ATDC (Close
Part Numbers CCA-102-000-9R (Right)
CCA-102-000-9L (Left)
As with any stroker build, clearances must all be checked—making sure counterweights and rods/bolts clear the block. Do a full rotation and observe all clearances. The M-6010-BOSS50 block sports interference fit main caps. (Image/Jim Smart)
JGM is running a Livernois windage tray to keep windage to a minimum. (Image/Jim Smart)
This is a nice piece with good fit. The fit exception can often be clearance issues with stroker kits where the windage tray must be trimmed for clearance. (Image/Jim Smart)
JGM opted for Cometic cylinder head gaskets (1-HI429SP6040S left and 1-HI430SP6040S right), which will provide extraordinary good cylinder sealing. (Image/Jim Smart)
This is a stock Romeo cylinder head, which is considerably different than the Windsor head, which has different individual cam journal caps. (Image/Jim Smart)
The Romeo head has bridged cam journal caps for rigidity. It really is a toss-up to which head is better. Each has its advantages. (Image/Jim Smart)
The Romeo head, as well as the Windsor, has high-swirl chambers for an improved light-off across the piston for more complete combustion, the use of heat energy, and cleaner emissions. You will see the difference between this head and the Twisted Wedge head you’re about to see. There is a clear difference. (Image/Jim Smart)
The Trick Flow Twisted Wedge Race 195 heads are clearly different than the stock “PI” castings in every respect. With good healthy port work, the PI heads do a good job. These heads are perfect for big bore Modular engine builds fitted with superchargers and turbos—operating on high compression E85, big shot nitrous oxide, and other mega-power combinations. (Image/Jim Smart)
They sport unique combustion chambers with optimum intake valve positioning, OE “PI-style” intake ports, CNC-profiled combustion chambers, and CNC competition ported runners with a premium high resolution surface finish for incredible performance. (Image/Jim Smart)
The Trick Flow Twisted Wedge chamber is clearly different than the PI chamber with a relocated intake valve and nice refinements to the chamber. The result is the kind of power PI heads, even with a port job, won’t give you. (Image/Jim Smart)
Refined and CNC ported Race 195 intake runners offer a direct shot into the chamber. Yet, these ports will accommodate factory induction as well as a broad range of aftermarket induction systems designed for PI heads. No modifications are required. (Image/Jim Smart)
Exhaust ports get the same CNC port work for exceptional scavenging, which is every bit as important as the intake side. (Image/Jim Smart)
Closer inspection of the Race 195 head demonstrates improvements beyond state-of-the-art port work. Look at these cam journals, which are a Trick Flow exclusive and sport replaceable bearings. (Image/Jim Smart)
JGM has chosen to ARP stud both the mains and cylinder heads for exceptional security. One area of consideration is head studding in the F-Series trucks. If you stud these heads, engine removal will become necessary in the F-Series trucks because at least half the engine is under the cowl. (Image/Jim Smart)
Our completed long block is ready for final assembly. We like the look of these Twisted Wedge heads. (Image/Jim Smart)
Check out this this half-inch billet aluminum CNC machined rear block plate from Modular Motorsports Racing, which replaces the factory cast alloy rear main seal housing cover. It helps support the block and provides a stable location for the rear main seal to eliminate leaks while increasing block strength and stability. This guy is O-ringed to eliminate the use of sealants. (Image/Jim Smart)
Because this engine is expected to see 7,500 to 8,000 rpm, JGM wanted abundant oil volume from Melling’s #10176 high-volume oil pump with hardened internals. (Image/Jim Smart)
Early Modular engines were fitted with solid steel reluctor wheels (left). Otherwise, they have been fitted with the stamped steel reluctor wheel on the right. (Image/Jim Smart)
It is very important to note the proper direction of the reluctor teeth, which must be pointed toward the timing cover away from the chains. Pointing these teeth toward the chains will cause severe engine damage. (Image/Jim Smart)
Timing tensioners aren’t to be taken lightly. Opt for the best. Trick Flow offers complete timing chain kit assemblies for your Romeo or Windsor-based Modular. JGM opted for the complete Trick Flow Timing Set fitted with Comp #10246SET adjustable timing gears. (Image/Jim Smart)
JGM started this build with a carburetion versus EFI master plan—to extensively dyno test this Modular mule with carburetion, then, a switch to EFI. A heavy dyno room schedule has prohibited access. This is the Edelbrock #2838 single-plane Modular intake topped with Holley’s HLY-0-82751 750 cfm HP carburetor. (Image/Jim Smart)
The all-new aluminum Street HP weighs up to 40 percent less than conventional Holley carbs. (Image/Jim Smart)
Our completed 5.3L SOHC Modular looks terrific with its Trick Flow heads and valve covers—fired by MSD coil-on-plug ignition and scavenged with JBA shorty headers. As soon as we get this guy on JGM’s dyno, we will report the facts to you here at OnAllCylinders. (Image/Jim Smart)

Trick Flow Twisted Wedge Race 195 Cylinder Head Airflow Specs

Valve LiftCFM
Intake Airflow at 28"
Exhaust Airflow at 28"
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Author: Jim Smart

Jim Smart is a veteran automotive journalist, technical editor, and historian with hundreds of how-to and feature articles to his credit. Jim's also an enthusiast, and has owned and restored many classic vehicles, including an impressive mix of vintage Ford Mustangs.