The 1967 Chevrolet Impala stands as an icon of American automotive design—a full-size cruiser that combined bold styling with a comfortable ride. Beneath that long hood, however, the standard big-block engines of the era were already strong, but for enthusiasts seeking modern performance, the factory output often falls short. Targeting 400 horsepower is a realistic, rewarding goal that transforms the Impala from a boulevard cruiser into a genuine performer. At the heart of many such builds lies the Dart Iron Eagle cylinder head, a cost-effective cast-iron design that can flow enough air to support well over 400 hp. This expanded cost analysis breaks down every expense involved, from the heads themselves to supporting mods and labor, helping you budget for a reliable and powerful machine.

Why 400 Horsepower for a 1967 Impala?

Four hundred horsepower is a sweet spot for a car that weighs roughly 4,000 pounds. It provides strong acceleration and highway merging without requiring a radical, unreliable race engine. The 1967 Impala’s suspension and driveline can handle that power level with reasonable upgrades, making it a practical target. Moreover, many 427 and 454 big-blocks (or even a built small-block 350) can reach 400 hp with the right cylinder heads and camshaft. The Dart Iron Eagle heads are specifically engineered for big-block Chevys, offering airflow improvements over factory iron heads while retaining the durability needed for street and occasional track use.

Understanding the Dart Iron Eagle Heads

Dart Iron Eagle heads are aftermarket cast-iron cylinder heads designed to replace factory iron heads on Chevrolet big-block engines (BBC). They are not to be confused with aluminum alternatives; iron heads are heavier but more affordable and resistant to heat distortion. Dart makes several variants, including the 215cc, 230cc, and larger runner sizes. For a 400 hp target, the 215cc or 230cc versions are ideal, depending on displacement and camshaft choice.

Key features:

  • High-flow intake and exhaust ports – Dart claims flow improvements of 20–30% over stock oval-port BBC heads, depending on the specific casting.
  • Hardened valve seats – Compatible with modern unleaded fuel without requiring additive.
  • Angled spark plug location – Improves combustion chamber shape and reduces interference with headers.
  • Thicker deck surfaces – Reduce the risk of head gasket failure under high cylinder pressure.
  • Available bare or assembled – Bare heads (no valves, springs, retainers) cost less but require additional parts purchase and assembly labor.

For a budget-conscious build, the bare heads are tempting, but assembled heads save time and ensure proper fitting. We’ll account for both scenarios in cost analysis.

Initial Costs: Dart Iron Eagle Heads

Head Prices

Pricing varies by supplier, runner size, and whether they are bare or assembled. As of 2025, typical ranges are:

  • Bare castings: $1,000 – $1,500 per pair (common on Summitt Racing or Jegs)
  • Assembled with standard valves, springs, and seals: $1,200 – $2,000 per pair
  • Premium assembled versions (CNC-ported, larger valves): $2,200 – $3,000 per pair

For a 400 hp build, the standard assembled heads are sufficient. Expect to pay $1,400 – $1,800 for a reliable set from a reputable dealer.

Additional Required Parts if Buying Bare

If you buy bare heads, you’ll need to purchase:

  • Valves (intake and exhaust): $200 – $400
  • Valve springs and retainers: $100 – $250
  • Valve stem seals: $20 – $50
  • Spark plugs (if not included): $40 – $80
  • Head bolts or studs: $50 – $150
  • Head gaskets: $80 – $150

Total for bare head parts: $450 – $1,100. So with bare heads, total head cost becomes $1,450 – $2,600. However, you also need to pay for valve seat cutting, spring seat machining, or assembly labor unless you have the tools. In most cases, buying assembled heads is simpler and only slightly more expensive when factoring in machine shop costs.

Shipping and Taxes

Heads are heavy (approximately 50–60 lbs each). Shipping can cost $30–$100 depending on carrier. Sales tax (if applicable) adds 5–10%. Budget an additional $100–$200 for these fees.

Labor Costs for Installation

Installing cylinder heads on a big-block Chevy in an Impala is not a beginner job unless you have experience. Professionals typically charge $75–$150 per hour. The job includes removing the old heads, cleaning the block deck, installing new head gaskets, torquing the bolts, setting valve lash, and checking pushrod length (if cam is changed).

Labor time estimates:

  • Removal of existing intake, exhaust, accessories, and heads: 3–4 hours
  • Cleaning and inspection of block deck: 1 hour
  • Installation of new heads, gaskets, and torquing: 3–5 hours
  • Reassembly of intake, exhaust, and accessories: 3–4 hours
  • Possible valve lash adjustment and initial start-up: 1 hour

Total labor: 10–14 hours. At $75–$150/hr, the cost ranges from $750 to $2,100. However, many shops quote a flat rate for head replacement: typically $600–$1,200 for a big-block car. We’ll use a middle estimate of $900–$1,500 for this analysis.

DIY option: If you perform the work yourself, labor cost is $0 but you must invest in tools (torque wrench, head bolt socket, tap and die set) and possibly a shop manual. Tool investment: $150–$300.

Supporting Upgrades to Reach 400 Horsepower

Stock engines will not reach 400 hp with only head swap. You will need a combination of parts to match the increased airflow. Below are the typical modifications required, with realistic cost ranges. Prices are for quality aftermarket parts (not budget no-name brands).

1. Intake Manifold

Factory iron intake manifolds are heavy and restrict flow. An aftermarket aluminum dual-plane intake (like the Edelbrock Performer RPM or Weiand Stealth) will improve mid-range torque and top-end power. For a street-driven Impala, a dual-plane is recommended over a single-plane for better low-speed drivability.

  • Cost: $250 – $500 for new; $150 – $300 used
  • Gaskets and bolts: $30 – $60
  • Total: $300 – $560

2. Camshaft and Lifters

A performance camshaft is essential. For 400 hp with Dart Iron Eagle heads, a hydraulic flat-tappet (or hydraulic roller if converting) cam with duration around 220–230 degrees at 0.050” and 0.500–0.550” lift works well. Must include matching lifters.

  • Camshaft: $150 – $400
  • Lifters: $80 – $200
  • Timing chain set: $50 – $150
  • Total: $280 – $750

If upgrading to a hydraulic roller cam (better reliability, more aggressive profile), add $100–$200 for the conversion parts (thrust button, cam button).

3. Exhaust System

Factory exhaust manifolds are restrictive. Headers are recommended, but for an Impala with power steering and AC, clearance can be tight. Options:

  • Long-tube headers: $300 – $600 (must fit Impala; check brands like Hooker, Hedman)
  • Shorty headers: $200 – $400 (easier install but less top-end gain)
  • Full dual exhaust kit (mandrel-bent pipes, mufflers, hangers): $400 – $800
  • Total exhaust system: $600 – $1,400

Additional costs: gaskets, bolts, O2 sensor bungs if needed: $50 – $100.

4. Fuel System Enhancements

Stock mechanical fuel pump and carburetor may suffice at 400 hp if properly tuned, but many enthusiasts upgrade for safety and consistency.

  • High-volume mechanical fuel pump: $60 – $120
  • Electric fuel pump upgrade (including regulator and lines): $200 – $400
  • Carburetor upgrade (750 CFM vacuum secondary): $300 – $600
  • Fuel line kit (3/8” steel or aluminum): $80 – $200
  • Total: $640 – $1,320

5. Ignition System

Stock points ignition may not reliably fire high cylinder pressures. A performance distributor and coil are worth it.

  • HEI distributor (one-wire, high performance): $150 – $300
  • Coil (if not included): $40 – $100
  • Spark plug wires: $50 – $100
  • Total: $240 – $500

6. Cooling System

More power = more heat. Expect to upgrade radiator and fan if not already.

  • Aluminum radiator (3-row): $200 – $400
  • Electric fan and controller: $150 – $300
  • Total: $350 – $700

7. Tuning and Dyno Time

After assembling the engine, professional tuning on a chassis dynamometer ensures safe air-fuel ratios and ignition timing. Likely needed.

  • Dyno session (2-3 pulls, tune adjustments): $200 – $500
  • Carburetor jetting or EFI tuning: $100 – $300
  • Total: $300 – $800

Total Estimated Cost Summary

Let’s combine the low-end and high-end estimates for a complete 400 hp upgrade. Costs assume you buy assembled Dart Iron Eagle heads, have a shop install heads and tune the engine, and purchase all new supporting parts.

ComponentLow EstimateHigh Estimate
Dart Iron Eagle heads (assembled)$1,400$1,800
Shipping/tax on heads$100$200
Head gaskets & bolts$130$200
Installation labor (heads)$900$1,500
Intake manifold & gaskets$300$560
Camshaft, lifters, timing set$280$750
Exhaust system (headers + exhaust)$600$1,400
Fuel system upgrades$640$1,320
Ignition system$240$500
Cooling system upgrades$350$700
Tuning & dyno$300$800
Grand Total$5,240$9,730

Note: This does not include potential machine work (e.g., block prep, piston/rod upgrades) if you are starting from a worn engine. For a running engine in decent condition, the above costs are realistic. If the engine requires a rebuild (rings, bearings, etc.), add $1,500–$3,000.

Alternative Paths and Cost Savings

1. Buying Used Parts

Used Dart Iron Eagle heads sometimes appear on forums or eBay. A used pair might cost $800–$1,200. Caveat: inspect for cracks, warped decks, or damaged threads. Similarly, used intake manifolds, camshafts, and headers can cut costs by 30–50%.

2. Choosing Cheaper Cylinder Heads

Other cast-iron heads like GM Performance Parts “641” or “049” castings can be found for $400–$800, but they require porting and larger valves to reach 400 hp. The machining cost may offset the lower initial price. Dart Iron Eagles offer good flow out of the box.

3. Doing the Work Yourself

Labor costs dominate the estimate. If you can install heads, cam, intake, and exhaust yourself, you save $1,500–$3,000. However, proper torque procedures and clearances demand mechanical skill and tools.

Benefits of Upgrading to 400 HP

  • Dramatic performance improvement: 0–60 mph times drop from ~10 seconds to ~5–6 seconds with proper gearing.
  • Improved drivability: modern heads and cam can provide stronger vacuum for brakes, better idle quality than a race cam.
  • Increased reliability: new valves, seats, springs eliminate 50-year-old wear, reducing risk of dropped valves.
  • Enhanced fuel efficiency: efficient combustion can actually improve highway MPG (expect 12–15 MPG vs 8–10 MPG stock).
  • Higher resale value: a well-documented performance build can add $3,000–$5,000 to the car’s value, often offsetting the upgrade cost.

Potential Pitfalls to Budget For

Several hidden costs may arise:

  • Valve clearance issues: Aftermarket heads may require different pushrod lengths or rocker arms (add $100–$300).
  • Oil pan clearance: Some intake manifolds or headers require a different oil pan (add $100–$250).
  • Transmission/torque converter upgrade: Stock TH400 or Powerglide may handle 400 hp, but a stall converter can improve launch (add $300–$600).
  • Rear axle strength: 10-bolt rear ends in Impalas are marginal; consider a limited-slip differential or 12-bolt swap ($500–$1,500).

External Resources

For additional information and parts sourcing:

Conclusion

Upgrading your 1967 Chevy Impala to 400 horsepower using Dart Iron Eagle heads is an achievable project with a budget typically falling between $5,000 and $10,000 for a turn-key installation with all supporting modifications. The investment yields a significantly more exciting car that retains its vintage character while delivering modern performance. By carefully selecting parts and tackling some labor yourself, you can keep costs at the lower end while still achieving a reliable, healthy power increase. Whether you are restoring the car or building a weekend cruiser, this cost analysis provides a realistic roadmap. Start with the heads, build around them, and enjoy the transformation of your classic Impala into a true muscle machine.