14/12/2014
The Enduring Appeal of the Ford Flathead V8
The Ford Flathead V8, often affectionately called the "Flattie," holds a special place in the hearts of automotive enthusiasts. Its distinctive V8 configuration, introduced by Ford in 1932, revolutionised engine design and became synonymous with American automotive innovation. For decades, it powered everything from everyday Fords to the burgeoning hot rod scene. This article delves into the intricacies of rebuilding a Ford Flathead V8, drawing insights from experienced builders and offering guidance for those embarking on their own restoration or modification projects.
We'll explore the process of sourcing and preparing a Flathead engine, the critical decisions involved in selecting components, and the finer points that can make the difference between a good rebuild and a truly exceptional one. Whether you're aiming for a period-correct restoration or a high-performance street rod, understanding the nuances of the Flathead is key to achieving your goals.
Understanding the Ford Flathead V8 Generations
Ford produced Flathead V8 engines for over two decades, and during this time, several distinct generations emerged, each with its own characteristics and suitability for different applications. Recognizing these differences is the first crucial step in planning your rebuild.
| Generation | Years | Key Features | Typical CID |
|---|---|---|---|
| First Generation | 1932-1937 | 21-stud blocks, 3 1/16" bore, poured babbit main bearings | 221 cu in |
| Second Generation | 1938-1948 | 24-stud blocks, improved water pump location, some with insert bearings | 221 cu in (Ford), 239 cu in (Mercury) |
| Third Generation | 1949-1953 | 8BA/8CM blocks, improved cooling, no integrated bell housing, insert bearings | 239 cu in (Ford), 255 cu in (Mercury) |
All Flatheads are not the same. The choice of engine block significantly influences the potential of your build. For instance, a dependable 21-stud engine from the early years is ideal for a tour-quality restoration of a 1932-1936 Ford. If you're aiming for a traditional hot rod with a bit more grunt, a 1937 21-stud or early 24-stud 221 cu in engine (1938-1939) offers a good balance of performance and originality. For those seeking substantial power increases, the 239 cu in engines, particularly the later 59A blocks (1946-1948), are favoured due to their ability to accommodate larger bores and strokes. The most desirable for modified builds are often the third-generation 8BA/8CM blocks (1949-1953) due to their newer manufacturing dates, improved cooling systems, and easier transmission compatibility.
Selecting the Right Hardware: A Critical Decision
Much like assembling a meal from a diverse menu, choosing the right components for your Flathead build requires careful consideration of how each part complements the others. The engine block is the foundation, and your choice here will dictate many subsequent decisions.
The Engine Block: The Heart of Your Build
The block is arguably the most critical element. For early builds where year-correct numbers aren't a primary concern, a late 1936 LB block with its larger insert crankshaft main bearings is an excellent choice for an economical and efficient rebuild. You can even incorporate a 1937 block, moving the water pumps to the block and using early water pump heads, a sensible upgrade that won't detract from the vintage appeal. Early first-generation engines (1932-1937) typically have a 3 1/16-inch bore, and it's advisable to limit overboring to 0.080 inch or less due to the castings' inherent thinness in some areas.
Second-generation 24-stud Ford blocks (1938-1942) also have a 3 1/16-inch bore and can accept stroked crankshafts. While they can be bored beyond 0.080 inch, they are still somewhat limited in their ultimate displacement potential. However, they readily accept a wide range of speed equipment, including heads, intakes, and camshafts. Mercury blocks, starting at 239 cu in, are more accommodating of larger bores and strokes.
The late second-generation 59A blocks (1946-1948), for both Ford and Mercury, have long been the favourite of builders. With a standard bore of 3 3/16 inch, they can be easily bored and stroked to exceed 300 cu in, though this can impact service life and cooling efficiency. The third and final generation (1949-1953) blocks, the 8BA and 8CM, are often the most sought-after for hot rod builds. Being the newest, they are more likely to be in better condition, feature improved cooling, and offer more modern transmission adaptability due to the absence of a cast-in half bell housing.
For those seeking a new beginning, the French-made blocks, originally produced for military applications, offer a pristine starting point. These are available in various stages of modification, from basic clearing to street-performance upgrades, and represent a significant investment in longevity and performance potential. While an investment, a desirable French block can significantly enhance the value of your finished engine.
Crankshafts and Connecting Rods: The Rotating Assembly
The choice of crankshaft and connecting rods is crucial for both reliability and performance. First-generation engines are generally paired with later first-generation crankshafts featuring full-floating connecting-rod bearings. Second-generation engines can utilize either full-floating or the third-generation's locked-insert bearings and rods.
Important distinction: Locked-insert bearings are not interchangeable with crankshafts designed for full-floating bearings. Locked-insert crankshafts have two oil feed holes per journal, while full-floating crankshafts have a single set that feeds the wider bearing accommodating both rods. Full-floating bearings can be used on the two-hole crankshafts, often in racing applications where reduced drag is beneficial.
While original Mercury 4-inch stroke crankshafts are becoming rare, modern aftermarket options from companies like SCAT and Eagle offer new stroker crankshafts and heavy-duty rods with strokes up to 4.250 inches. A complete stroker assembly can cost upwards of £1200, and is essential for high-output, supercharged engines. For more modest performance goals, a 3 3/4-inch French crankshaft paired with 8BA style rods offers a more budget-friendly alternative.
Pistons: The Heart of Combustion
Piston selection depends heavily on your performance objectives. Options range from OEM-style four-ring cast pistons, favoured by restorers for their quiet operation, to cast or hypereutectic three-ring pistons for stock to street-performance builds. For high-performance and supercharged applications, forged pistons are essential due to their superior strength and durability. Forged pistons expand more than cast units, requiring larger clearances, which can lead to increased noise until the engine reaches operating temperature. Unless the demands of your build necessitate forged pistons, cast units are generally recommended for their quieter operation.
Camshafts and Valvetrain: Dictating Engine Character
The camshaft is the primary determinant of an engine's personality. A mild "3/4 race" camshaft can significantly awaken a stock engine, especially when paired with a second carburetor and some minor head milling, creating a noticeable increase in perceived power. However, choosing a camshaft that is too aggressive for the engine's potential or your intended use can lead to poor drivability and disappointing performance.
The key is balance. Select a camshaft that matches your needs and complements your engine modifications. Avoid choosing a cam solely for its aggressive idle "lope." While this sound can be appealing, it often comes at the cost of drivability and fuel economy. It's wise to consult with camshaft specialists like Iskenderian or Schneider for expert advice tailored to your specific project.
Cylinder Heads: Optimising Breathing
Original cast-iron cylinder heads, when properly cleaned and milled (no more than 0.010-0.020 inch), can offer a modest increase in compression ratio without significantly hindering flow. The combustion chamber design in most Ford heads is generally good, often superior to some older aftermarket aluminum heads. The availability of usable vintage aluminum heads is diminishing, with most requiring significant repair work. Unless you have a specific desire for a particular set of vintage heads, purchasing new aluminum heads from reputable manufacturers is often a more cost-effective and reliable solution.
Carburetion and Intake Manifolds: Fueling the Beast
For most street-performance Flathead engines up to 255 cu in, a dual-carburetor setup is optimal. Three- and four-carburetor configurations are typically reserved for larger displacement engines and racing applications, as they can lead to poor drivability and fuel economy on the street, even with progressive throttle linkages.
Dual-plane intake manifolds, often based on Ford's original designs, are generally a good choice. Early aftermarket open-plenum manifolds should be approached with caution due to potential drivability issues. For a good balance of performance, economy, and simpler installation, matched four-barrel carburetor and manifold systems from manufacturers like Edelbrock and Speedway can be an excellent alternative to dual-carb setups, often at a lower cost.
Ignition Systems: Sparking the Fire
Ignition choices are straightforward: either a traditional mechanical breaker-point system or a more modern electronic ignition. The pros and cons of each are detailed in more comprehensive technical guides, but electronic ignition generally offers improved reliability and reduced maintenance.
Supercharging the Flathead
Supercharging a Ford Flathead V8 is a specialised topic that warrants in-depth study. For those interested in this path, resources like Joe Abbin's "Flathead Ford V-8 Performance Handbook" provide extensive information on building streetable blown Flathead engines. This is a complex modification that requires careful attention to component strength and tuning.
Where to Source Your Parts
While the days of single-source "one-stop shopping" for all Flathead components are largely past, companies like Speedway Motors still offer a vast array of parts. Additionally, numerous specialists cater to specific needs, providing expertise and components for carburetion, camshafts, crankshafts, cylinder heads, and intake manifolds. Consulting appendices in dedicated Flathead rebuild books or online directories can help you locate these specialized suppliers.
Conclusion: A Rewarding Endeavour
Rebuilding a Ford Flathead V8 is a deeply rewarding project that connects you with a significant piece of automotive history. By understanding the different engine generations, carefully selecting your components, and paying attention to the finer details, you can create an engine that not only looks and sounds authentic but also performs reliably for years to come. The journey of a Flathead rebuild is as much about the process and the learning as it is about the final, roaring result.
Frequently Asked Questions
Q1: How much does it typically cost to rebuild a Ford Flathead V8?
A1: The cost can vary significantly depending on the condition of the original engine, the extent of modifications, and the quality of parts used. A basic, professionally rebuilt 59A engine to standard specifications might cost around £3000-£4000. However, a high-performance or race-oriented build with custom components and machining can easily run into £7000-£10,000 or more.
Q2: Are French Flathead blocks worth the extra cost?
A2: For serious builders aiming for longevity and a high-quality foundation, French blocks are often considered a worthwhile investment. They are typically in better condition than many salvaged blocks and offer a clean slate for modifications. Their scarcity also adds to their desirability and future value.
Q3: What is the best camshaft for a street-driven Flathead?
A3: The "best" camshaft is subjective and depends on your specific build and driving habits. A mild "3/4 race" grind is often a good starting point for a street performance engine, offering a noticeable improvement over stock without sacrificing too much drivability. Consulting with camshaft manufacturers is highly recommended.
Q4: Can I use modern transmission with an early Flathead?
A4: Adapting modern transmissions to early Flathead engines often requires custom bell housings or adapter plates. The third-generation 8BA/8CM blocks are more amenable to modern transmission swaps due to the absence of the integrated bell housing.
Q5: How do I identify the generation of my Ford Flathead V8?
A5: Key identifiers include the number of "studs" on the cylinder heads (21 or 24), the casting date codes on the block, and the design of the water pumps (in the heads for early engines, in the block for later ones). The bore size and bearing type are also strong indicators.
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