The 428 Cobra Jet engine represents a golden era of American muscle, a time when displacement was king and the quarter-mile was the ultimate proving ground. Think about it: for collectors, restorers, and performance enthusiasts hunting for a 428 Cobra Jet engine for sale, the journey is as much about historical preservation as it is about raw horsepower. Finding a genuine, numbers-matching block requires patience, knowledge, and a keen eye for detail, because the market is flooded with replicas, misidentified standard 428s, and pieced-together assemblies that lack the pedigree of a true Ford performance legend That's the part that actually makes a difference. Took long enough..
The Legend of the 428 Cobra Jet
Introduced mid-year in 1968, the 428 Cobra Jet (often referred to as the 428 CJ or simply "CJ") was Ford’s answer to the Chrysler Hemi and the GM big-blocks dominating the streets and strips. Day to day, unlike the standard 428 Police Interceptor, the Cobra Jet was engineered specifically for drag racing right off the showroom floor. It featured a unique combination of heavy-duty internals, improved breathing, and a ram-air induction system that made it an instant icon.
The heart of the engine was the 428 cubic inch (7.The cylinder heads were a specific casting (C8OE-H) featuring larger valves (2.0L) FE block, but the magic lay in the details. Day to day, ford equipped the CJ with 427-style "LeMans" capscrew connecting rods, a nodular iron crankshaft (in early production), and heavier main bearing caps. 66" exhaust) and improved port geometry compared to standard 428 heads. 09" intake / 1.Topping it off was a 735 CFM Holley 4150 carburetor on a dual-plane aluminum intake manifold (C8OE-9425-C), often paired with the famous Ram Air induction system that routed cold air directly from the hood scoop to the air cleaner.
When you begin searching for a 428 Cobra Jet engine for sale, understanding these factory specifications is your first line of defense against buying a lesser engine dressed up to look like the real thing.
Identifying a Genuine 428 Cobra Jet Block
The single most critical step in verifying a potential purchase is decoding the casting numbers and date codes. A true Cobra Jet block will carry the casting number C8AE-6015-C (or occasionally C8AE-6015-D for later service replacements) on the passenger side of the block, near the starter. That said, the casting number alone isn't enough, as standard 428 blocks share similar external architecture Practical, not theoretical..
You must look for the engine assembly stamp on the front passenger side pad of the block (machined surface near the timing cover). * Letter (K): Assembly plant (K = Cleveland Engine Plant #2, where all CJs were built).
- First digit (8): Model year 1968. In practice, a genuine CJ stamp will read something like 8K01R or similar. Think about it: * Numbers (01): Day of the month. In real terms, * Suffix (R): The engine code. R-code signifies the 428 Cobra Jet with Ram Air. A Q-code signifies the 428 Cobra Jet without Ram Air (standard hood), which is rarer but still a genuine CJ.
If the suffix code is missing, stamped over, or shows a code like 'P' (428 Police Interceptor) or 'Z' (428 standard), it is not a factory Cobra Jet. Be extremely wary of blocks that have been "restamped." Expert restampers exist, but the font, depth, and patina of the original stamp are difficult to replicate perfectly.
Critical Components to Verify
Beyond the block itself, a complete 428 Cobra Jet engine for sale should ideally include the correct date-coded peripherals. The value drops significantly if the engine is "correct but not numbers-matching" versus a fully documented, numbers-matching unit That's the part that actually makes a difference..
Cylinder Heads
Look for the C8OE-H casting number on the top of the head, between the valve springs. These are the only factory heads that came on the 428 CJ. They feature the larger valves and specific combustion chamber shape (approx. 73-76cc). Many engines for sale have had these swapped for aftermarket aluminum heads (like Blue Thunder or Edelbrock) or the later 429/460 style conversions. While aftermarket heads flow better, they destroy the collector value of a restoration-grade engine.
Intake Manifold
The factory intake is an aluminum dual-plane casting C8OE-9425-C. It is distinct from the standard 428 iron intake or the 427 "Top Oiler" intakes. It was designed specifically for the Holley 4150 carburetor spread bore pattern (though the CJ Holley is a square bore 4150, the manifold accepts it). Check for the casting date code on the front runner; it should precede the engine assembly date by a few weeks or months.
Crankshaft and Rods
Early 1968 production (roughly before April 1968) received a nodular iron crankshaft (casting 1UA or 1UAB), identifiable by a small "N" or diamond mark on the counterweight. Later production switched to a standard cast iron crank (casting 2YABC) but retained the 427-style capscrew rods (C8AE-6200-A). If the engine is apart, verify the rod bolts are the specific 3/8" capscrew style, not the standard 5/16" bolt/nut style found in standard 428s.
Exhaust Manifolds
True CJ exhaust manifolds are specific high-flow cast iron units (C8OE-9430/31-C/D) designed to clear the shock towers on Mustangs and Cougars while flowing better than standard 428 logs. They are often reproduced, but originals carry specific casting numbers and date codes.
Where to Find a 428 Cobra Jet Engine for Sale
Locating one of these powerplants rarely happens at a local junkyard anymore. The primary marketplaces have shifted to specialized platforms Not complicated — just consistent. Took long enough..
1. Specialized Muscle Car Classifieds: Websites like Hemmings, ClassicCars.com, and OldRide.com often have dedicated sections for engines and drivetrain components. Sellers here usually understand the value of casting numbers and documentation.
2. Ford-Specific Forums and Registries: The FE engine community is tight-knit. Forums like FordFE.com, the FE Forum on FordMuscleForums.com, and the Cobra Jet Registry are excellent places to find "insider" deals. Engines sold here often come with build sheets, dyno sheets, and known history.
3. High-End Auctions: Mecum, Barrett-Jackson, and Bonhams occasionally list bare blocks, long blocks, or complete turn-key engines during their major events. These are usually vetted by experts, but buyer premiums add 10-15% to the hammer price That's the whole idea..
4. Specialist Engine Builders/Restorers: Shops like Kaase Racing Engines, Survival Motorsports, or smaller FE specialists occasionally take consignments or have "take-out" engines from customer cars being upgraded to aftermarket blocks. Buying from a reputable builder offers a warranty and professional assembly verification that a private seller cannot Not complicated — just consistent..
Pricing Expectations in the Current Market
The value of a 428 Cobra Jet engine for sale varies wildly based on completeness, condition,
...completeness, condition, and provenance. As of the current market, expect the following general tiers:
Bare Block (Verified CJ Casting C8OE-6015-C)
- Standard Bore/Needs Machining: $3,500 – $6,000. Value hinges entirely on sonic checking results (cylinder wall thickness) and a clean magnaflux report. Cracks in the lifter valleys or main webs drop the price to core value ($1,500).
- Freshly Machined (Bored/Honed/Deck/Align-Honed): $7,000 – $10,000+. Includes receipts from a known FE specialist.
Rotating Assembly (Crank/Rods/Pistons)
- Nodular Iron Crank (1UA/1UAB) + Capscrew Rods: $2,500 – $4,000 for a standard-size, magnafluxed, polished set. The "N" mark crank commands a premium over the later 2YABC cast crank ($1,200 – $1,800).
- Aftermarket Forged Stroker Kits (4.150" or 4.250" Stroke): Often cheaper than restoring original rods, but purists discount the engine value significantly if the original rotating assembly is missing.
Cylinder Heads (C8OE-6090-N/R or -H/J)
- Raw, Unchecked Castings: $1,500 – $2,500/pair. High risk of cracked exhaust seats or excessive guide wear.
- Rebuilt/Refreshed (New Seals, Guides, Seats, Valve Job): $3,500 – $5,000/pair.
- Ported/Flow-Bench Developed (by known FE porters): $6,000 – $9,000+/pair. These add significant performance value but may detract from "numbers-matching" concours value.
Complete Long Block (Block, Crank, Rods, Pistons, Heads, Cam, Timing Set, Oil Pump)
- “Core” Long Block (Unknown Condition/Seized): $6,000 – $9,000. A gamble; budget for a full teardown and $8k–$12k in machine work/parts.
- Fresh Professional Rebuild (Receipts, Dyno Sheet, Break-in Oil): $18,000 – $28,000. The sweet spot for turnkey reliability.
- Concours-Correct / NOS Restoration: $35,000 – $50,000+. Assembled with date-correct hardware, original paint marks, FoMoCo filters, and correct smog/thermactor provisions (if applicable). These engines rarely trade hands publicly.
The "CJ vs. SCJ" Premium A verified Super Cobra Jet (Drag Pack) engine—identified by the external oil cooler boss on the block (C8OE-6015-D or later service block with boss), 427-style "LeMans" capscrew rods (often with 7/16" bolts in later service replacements), and specific piston cooling notches—commands a 20–35% premium over a standard CJ long block in equivalent condition.
Critical Inspection Checklist: Before You Wire Money
If you are inspecting an engine in person—or asking a proxy to do so—verify these non-negotiables. Photos lie; casting numbers and machining marks do not No workaround needed..
1. The Block "Birth Certificate"
- Casting Number: C8OE-6015-C (Standard CJ) or C8OE-6015-D (SCJ/Drag Pack boss). Note: Ford service replacement blocks (D0OE, D1OE) are excellent for building but kill concours value.
- Date Code: Located on the rear face of the block near the bellhousing flange (e.g., 8A15 = Jan 15, 1968). Must precede the vehicle build date by 2–8 weeks.
- Main Cap Numbers: Caps should be numbered 1–5 (front to rear) with matching "arrow" orientation marks. Mismatched caps suggest a line-bore on a junkyard block.
2. The Head Casting & Date Reality
- Casting Number: C8OE-6090-N or **-R
