Why the Eagle Stroker Kit Delivers 100+ Horsepower Gains

The Eagle Stroker Kit is engineered to increase engine displacement by utilizing a longer-stroke crankshaft combined with forged pistons and connecting rods. This combination allows the engine to draw in and burn more air and fuel per cycle, directly translating into a horsepower increase of 100 HP or more on properly prepared platforms. Whether you are building a street performance car or a weekend drag racer, this kit offers a proven path to substantial power gains without requiring a complete aftermarket block.

However, the installation process demands mechanical competence, careful attention to clearances, and a methodical approach. Rushing any step can lead to catastrophic engine failure. This guide provides a detailed, step-by-step walkthrough so you can complete the swap with confidence and achieve reliable, high-performance results.

Tools and Materials You Will Need

Before turning a single bolt, gather all necessary tools and components. Having everything on hand prevents unnecessary delays and ensures you maintain focus during the installation.

Essential Tools

  • Socket set – both SAE and metric, ranging from 8 mm to 24 mm, with deep-well and standard sockets
  • Torque wrench – a quality click-type or beam-style wrench capable of 10–150 ft-lb range
  • Engine hoist – minimum 1-ton capacity with adjustable chains or leveler
  • Engine stand – to safely support the block during assembly
  • Piston ring compressor – sized to match your new piston diameter
  • Plastigauge – for checking bearing clearances
  • Feeler gauges – for verifying ring end gap and camshaft timing
  • Dial indicator and magnetic base – for verifying crankshaft end play
  • Degreaser and shop rags – for cleaning machined surfaces

Components and Consumables

  • Eagle Stroker Kit – includes forged crankshaft, connecting rods, pistons, piston rings, and bearings
  • Gasket set – complete top-end and bottom-end gasket set with intake, exhaust, and oil pan gaskets
  • Timing chain and gears – heavy-duty double-roller set recommended
  • Oil pump – high-volume or standard replacement as required by your application
  • Engine oil and filter – break-in oil with high zinc content (e.g., 10W-40 or 15W-50) and a quality oil filter
  • Coolant – 50/50 mix of distilled water and ethylene-glycol antifreeze
  • Thread locker – medium-strength (blue) for critical bolts
  • Assembly lube – for coating bearings, cam lobes, and lifter faces during initial assembly

Safety Gear

  • Safety goggles – impact-resistant
  • Mechanics gloves – cut-resistant with good dexterity
  • Steel-toe boots – for heavy component handling

Preparation: Setting Up Your Workspace and Vehicle

Proper preparation minimizes the chance of mistakes and ensures a smooth installation process. Take the time to set up your workspace correctly before removing anything.

  1. Park the vehicle on a level, solid surface – concrete or asphalt is ideal. Engage the parking brake and chock both rear wheels to prevent any movement.
  2. Disconnect the battery – remove the negative (ground) terminal first, then the positive terminal. This prevents accidental shorts, sparks, or electrical damage while working near the starter, alternator, and sensors.
  3. Drain all fluids – drain the engine oil by removing the drain plug, and drain the coolant by opening the radiator petcock. Dispose of all fluids in accordance with local regulations.
  4. Remove external components – take off the hood (bonnet), air intake assembly, radiator and cooling fan, and the exhaust manifolds or headers. Label and bag all fasteners to simplify reassembly.
  5. Support the vehicle – if you need to access the underside, use quality jack stands rated for the vehicle weight. Never rely on a jack alone.
  6. Prepare the engine hoist – attach the lifting chains or leveler to the engine lift points. Make sure the hoist is positioned so you can lift the engine straight up without interference.

Once the workspace is ready and the engine bay is clear, you can begin removing the old engine components. Work methodically and keep your workbench organized.

Removing the Old Engine Components

To install the Eagle Stroker Kit, the engine must be stripped down to a bare block. If you are working on an engine still in the vehicle, you may find it easier to remove the entire engine and mount it on a stand. Below is the sequence for a typical V-8 or inline-six application.

Step 1: Remove Intake and Exhaust Systems

  • Unbolt the intake manifold and carburetor or throttle body. On fuel-injected engines, disconnect the fuel lines and electrical connectors carefully.
  • Remove the exhaust headers or manifolds. Soaking the exhaust bolts with penetrating oil beforehand will help prevent breakage.

Step 2: Detach Accessories and Front Accessories

  • Remove the alternator, power steering pump, and air conditioning compressor (if equipped). Do not discharge the AC system unless necessary; simply unbolt and set aside.
  • Remove the water pump, harmonic balancer, and timing cover.

Step 3: Take Out the Cylinder Heads

  • Loosen the cylinder head bolts in the reverse of the specified torque sequence. Gradually work in stages to avoid warping the heads.
  • Lift the heads off and set them on a clean surface. Mark each head (left/right or front/back) to maintain proper orientation.

Step 4: Remove the Oil Pan and Timing Components

  • Turn the engine upside down on the stand (or reach underneath if still in the vehicle) and unbolt the oil pan.
  • Remove the oil pump, pickup tube, and timing chain tensioner.
  • Remove the camshaft timing gear and chain. Keep the old chain for reference.

Step 5: Extract the Old Pistons and Crankshaft

  • Rotate the engine so the connecting rod caps are accessible. Unbolt each cap and push the pistons out through the top of the block. Use a wooden or plastic hammer handle to gently tap stubborn pistons.
  • Remove the main bearing caps in sequence (usually 1–5 or 1–4 from front to back). Lift out the old crankshaft and set it aside.
  • Remove the old main bearings and rod bearings. Inspect the bearing surfaces for signs of wear or failure—this can reveal pre-existing oiling or alignment issues.

Thoroughly clean the engine block after disassembly. Remove all old gasket material, and clean the cylinder bores with a degreaser and brake cleaner. Blow out all oil passages with compressed air.

Installing the Eagle Stroker Kit

With the block clean and prepped, it is time to install the stroker components. Precision and cleanliness are paramount; even a small piece of debris can destroy a bearing in seconds.

Step 1: Install the New Main Bearings and Crankshaft

  • Install the upper main bearing inserts into the block. Ensure the bearing tangs align with the machined slots. Apply a thin coat of assembly lube to all bearing surfaces.
  • Lower the new forged crankshaft into the block. Rotate it by hand to check for smooth operation.
  • Install the lower main bearing inserts into the main caps. Lubricate them with assembly lube.
  • Torque the main bearing cap bolts to the specifications provided by Eagle (typically 65–80 ft-lb for most V-8 applications). Use a three-step torque sequence: 30 ft-lb, then 60 ft-lb, then final spec.
  • Check crankshaft end play using a dial indicator. Acceptable end play is usually 0.005–0.007 inch. If out of spec, inspect the thrust bearing for proper seating.

Step 2: Prepare and Install the New Pistons and Connecting Rods

  • Check the piston ring end gap before installation. Insert each ring into its respective cylinder bore and use a feeler gauge to confirm the gap matches Eagle's recommendations (typically 0.020–0.025 inch for the top ring on a street stroker).
  • Install the rings onto the pistons using a ring expander tool. Stagger the ring gaps evenly around the piston (e.g., 120 degrees apart) to minimize blow-by.
  • Attach the pistons to the connecting rods using the wrist pins. Ensure the piston orientation matches the rod's offset (most rods have a chamfer that must face the crankshaft counterweight).
  • Lubricate the cylinder bores and piston skirts with assembly lube or engine oil.
  • Compress the rings using a ring compressor, then carefully tap each piston into its bore with a wooden hammer handle. Keep the connecting rod aligned with the crankshaft journal.
  • Install the rod bearings (with assembly lube) and torque the rod cap bolts to Eagle's specification (typically 45–55 ft-lb for 3/8-inch bolts).
  • Rotate the crankshaft by hand after each piston to verify free movement. Any binding indicates a misalignment or incorrect clearance.

Step 3: Install the Timing Components and Oil Pump

  • Install the new camshaft (if your kit includes one) following the manufacturer's break-in procedure. Lubricate the cam lobes thoroughly with break-in lube.
  • Align the crankshaft and camshaft timing marks according to the timing set instructions. The marks should be positioned at TDC (top dead center) for cylinder 1.
  • Install the double-roller timing chain and gears. Torque the camshaft gear bolt to the specification provided by Eagle or your block manufacturer.
  • Install the new oil pump. Most Eagle kits use a standard-volume or high-volume pump. Pack the pump with petroleum jelly or assembly lube to prime it before installation.
  • Install the oil pump pickup tube and screen, ensuring it clears the oil pan and sits approximately 1/4 inch above the pan floor.

Step 4: Install the Cylinder Heads

  • Use new head gaskets that match your engine's bore size. Some stroker kits require a 4.125-inch bore gasket or larger; verify the gasket opening does not intrude into the combustion chamber.
  • Place the cylinder heads on the block and install the head bolts. Lubricate the bolt threads and washers with engine oil.
  • Torque the head bolts in the manufacturer's recommended sequence and torque specification. Use a three-pass method (50%, 75%, 100% of final torque) to ensure even clamping.

Step 5: Install the Valve Train

  • Install new valve springs, retainers, and keepers if your stroker build includes upgraded springs. Verify spring height and installed pressure using a spring tester.
  • Install pushrods and rocker arms. Adjust the valve lash (if using mechanical lifters) or verify the hydraulic lifter preload (typically 0.020–0.060 inch) with an adjustable pushrod length checker.

Reassembling the Engine

With the Eagle Stroker Kit installed, it is time to put the rest of the engine back together. Follow these steps in order to avoid missing critical fasteners or gaskets.

  1. Install the timing cover and water pump – use a new timing cover gasket and seal. Apply a small bead of RTV silicone at the corners of the oil pan and timing cover interface.
  2. Install the oil pan – use a new gasket and torque the pan bolts to 10–15 ft-lb in a crisscross pattern. Do not overtighten; the pan can distort and cause leaks.
  3. Reinstall the intake manifold – use a new gasket set. Apply a thin bead of RTV at the front and rear valleys where the gasket meets the block. Torque the intake bolts to the factory specification in the correct sequence.
  4. Attach the exhaust headers – use new gaskets and install the header bolts with a small amount of anti-seize compound. Torque evenly from the center outward.
  5. Install the carburetor or throttle body – use a new gasket and connect the fuel lines, vacuum lines, and throttle linkage.
  6. Reconnect the cooling system – install the radiator, fan, and hoses. Fill the system with a 50/50 coolant mix.
  7. Install the accessories – reattach the alternator, power steering pump, and any other components removed earlier. Tighten belts to the appropriate tension.
  8. Install the oil filter and fill the engine with oil – use a break-in oil formulated for flat-tappet or roller cams as appropriate. Fill the engine with 5–6 quarts (adjust for your specific oil pan capacity).
  9. Reconnect the battery – attach the positive terminal first, then the negative. Double-check all electrical connections.

Testing the Installation

Before you take the vehicle on the road, you must perform a thorough test of the installation. A careful startup procedure can reveal problems before they cause damage.

Initial Startup Procedure

  1. Prime the oil system – if possible, use a priming tool and a drill to spin the oil pump and build oil pressure before the first start. Crank the engine with the ignition disabled until the oil pressure gauge registers.
  2. Start the engine – set the idle to around 1,000 RPM. Listen for any unusual noises, such as knocking, ticking, or rattling. If you hear anything suspicious, shut the engine off immediately and investigate.
  3. Check for leaks – inspect the oil filter, oil pan gasket, timing cover, and coolant hoses for any signs of fluid leakage. Tighten or replace gaskets as needed.
  4. Monitor gauges – allow the engine to reach operating temperature. Watch the oil pressure gauge (should read 40–60 psi at idle once warm) and the coolant temperature gauge (should stabilize around 190–210°F).
  5. Perform a camshaft break-in – if your engine uses a flat-tappet camshaft, vary the engine speed between 2,000 and 3,000 RPM for the first 20 minutes. Do not let the engine idle for extended periods during break-in.

After the initial run, let the engine cool completely, then re-torque the cylinder head bolts and intake manifold bolts. Also check and adjust the valve lash if necessary.

Tuning the Engine for Maximum Performance

The Eagle Stroker Kit increases displacement, which fundamentally changes the engine's air and fuel requirements. Proper tuning is essential to unlock the full 100+ HP gain.

Carburetor or EFI Adjustments

  • A larger displacement engine requires more fuel. You will likely need to increase jet sizes in a carburetor or adjust the fuel map in an EFI system. A good starting point is to go up 4–6 jet sizes on both the primary and secondary circuits.
  • Check the air-fuel ratio with a wideband oxygen sensor. Target 12.5–13.0:1 at wide-open throttle for maximum power on pump gas.
  • Adjust the idle mixture screws for the highest vacuum reading on the manifold gauge.

Ignition Timing

  • Larger engines typically require less initial timing. Start with 10–12 degrees of initial advance and adjust based on detonation testing.
  • Verify the total mechanical advance (initial + centrifugal) does not exceed 34–36 degrees at 3,000 RPM. Use a timing light to confirm.
  • If using a vacuum advance, connect it to a manifold vacuum source and set the advance for 10–15 degrees at idle.

Professional Dyno Tuning

For the best results, consider a professional dyno tune after you have completed the installation and initial break-in. A dyno session allows a skilled tuner to optimize the fuel curve, ignition timing, and distributor curve for your specific combination. The investment often yields an additional 10–20 HP over a rough street tune and ensures reliable operation. For more information on professional tuning services, consult a reputable shop listed on the Summit Racing product page for your specific Eagle kit.

Final Thoughts

Installing the Eagle Stroker Kit is a labor-intensive but highly rewarding project. When executed correctly, the kit transforms your engine from a modest performer into a potent powerplant capable of 100+ HP increases. The combination of a forged crankshaft, high-quality connecting rods, and custom pistons provides both strength and reliability when you lean into the throttle.

Throughout the process, remember that precision matters. Check every clearance, torque every bolt to specification, and do not skip the break-in procedure. If you hit a snag, consult the detailed instructions included with your kit or refer to Eagle's official product page for application-specific specifications. For sourcing components and cross-referencing parts, JEGS offers a comprehensive selection of Eagle kits with customer reviews and fitment notes.

With patience, the right tools, and this guide, you can confidently install your Eagle Stroker Kit and enjoy the surge of horsepower that comes with a properly built stroker engine.