Introduction

Adding a stroker kit to your engine is one of the most effective ways to significantly increase displacement and horsepower. By increasing the crankshaft stroke and pairing it with longer connecting rods and custom pistons, a stroker kit can elevate a small-block engine into a torque monster. COMP Cams is a trusted name in performance engine components, and their stroker kits are engineered for durability and power. With careful installation, you can expect over 400 horsepower at the crank from a naturally aspirated build. This guide provides a comprehensive, step-by-step expansion on the installation process, covering every critical detail from initial tear-down to the first startup.

Tools and Materials

Before you begin, gather the following tools and supplies. Having everything on hand will prevent interruptions and ensure you work efficiently.

Required Tools

  • Complete socket and wrench set (metric and SAE)
  • Torque wrench (ft-lb and in-lb ranges)
  • Engine hoist and load leveler
  • Engine stand (if engine is removed)
  • Dial bore gauge and micrometer
  • Plastigauge for bearing clearance checks
  • Ring gap file and ring squaring tool
  • Piston ring compressor
  • Camshaft degree kit (if cam is also upgraded)
  • Harmonic balancer installer/remover
  • Gasket scraper and surface prep tools
  • Brake cleaner, shop rags, and assembly lube
  • Timing light (for final verification)

Materials and Components

  • COMP Cams stroker kit (crankshaft, connecting rods, pistons, rings, bearings)
  • Full gasket set (head gaskets, intake, exhaust, oil pan, timing cover)
  • New timing chain and gears (double-roller recommended)
  • Oil pump (high-volume if desired) and pickup tube
  • New oil and oil filter
  • Fresh engine coolant
  • New spark plugs (copper core for break-in recommended)
  • Fuel injectors (if original flow rate is insufficient for new displacement)
  • Thread-locking compound and sealant (e.g., RTV for oil pan corners)

If you plan to upgrade the camshaft along with the stroker kit, COMP Cams offers matched cam and lifter sets that pair well with their stroker components. Consult their application guide or call tech support to verify compatibility.

Preparation

Proper preparation sets the foundation for a successful build. Whether you are working on an engine in the vehicle or on a stand, these initial steps are critical.

Workspace and Safety

  • Work in a clean, well-lit area with enough room to maneuver.
  • Disconnect the battery negative terminal to prevent accidental starts or shorts.
  • Drain all engine oil and coolant into approved containers.
  • If the engine is still in the vehicle, remove the hood, radiator, and front accessories to access the engine bay fully.

While it is possible to install a stroker kit with the engine in the car by removing the oil pan and lifting the engine, it is far easier and safer to pull the entire engine. Use an engine hoist and leveler to remove the engine-transmission assembly or separate them. Mount the engine securely on a stand. This gives you unrestricted access to the bottom end and makes torqueing main and rod bolts more accurate.

Disassembly and Cleaning

  • Remove the intake manifold, carburetor/throttle body, and distributor.
  • Remove the exhaust headers or manifolds.
  • Take off the cylinder heads and store them with labeled fasteners.
  • Remove the oil pan, timing cover, and harmonic balancer.
  • Remove the oil pump and pickup tube.
  • Remove the camshaft if you are replacing it (note that some stroker kits do not include a cam, but many builders upgrade at the same time).
  • Clean the engine block thoroughly, paying attention to bolt holes and oil passages. Use brake cleaner and compressed air.

Pro tip: Magnaflux or pressure test the block if you suspect cracks. This is especially important when increasing displacement on high-mileage blocks.

Disassembly: Removing the Old Rotating Assembly

With the engine stripped to a short block, you can extract the original crank, rods, and pistons.

Marking and Organization

  • Number each connecting rod and cap with a center punch or marker to ensure they go back together in the same orientation (if reusing rods, which is not typical when upgrading to a stroker kit). Because you are replacing the rods, keep the old set as spares or cores.
  • Remove the main bearing caps and mark them with their position (1–5 or 1–4 depending on engine). Loosen bolts in a crisscross pattern to prevent warping the block.
  • Lift out the crankshaft carefully, and remove the rod/piston assemblies from the top after removing the rod bolts.
  • Keep bearings, caps, and fasteners organized if you plan to reuse the block for another build; otherwise, discard them.

Block Inspection and Machining

Before installing the new stroker components, the block must be inspected and often machined to accept larger parts. This is best done by a reputable engine machine shop.

  • Check cylinder bores for taper, ovality, and wear. Many stroker kits require a final bore and hone to match the new pistons. COMP Cams pistons often come with a specified bore size (e.g., 0.030” or 0.040” over).
  • Have the block decked if necessary to achieve the desired compression height and quench.
  • Clean and chase all bolt holes with a tap. Install main studs or ARP bolts if recommended by the kit instructions.
  • If the new crankshaft has a larger stroke, you may need to clearance the block’s lower skirts and/or the oil pan rails. Use a dummy crank or fit the crank and rotate it with a dial indicator to check clearance.

Refer to the COMP Cams stroker kit documentation for specific clearance requirements. Some YouTube channels like Powder Mountain Metalworks show block clearance procedures in detail.

Installing the COMP Cams Stroker Kit

Once the block is prepped and machined, it’s time to assemble the rotating assembly. Work in a clean environment and wear gloves to keep oil and grit off the bearings.

Installing the Main Bearings and Crankshaft

  1. Install the main bearing inserts into the block and main caps. Ensure the oil holes align. Apply assembly lube to the bearing surfaces.
  2. Carefully lower the COMP Cams crankshaft into place. Stroke cranks often have larger counterweights, so rotate the crank by hand to verify clearance at the bottom of the cylinders and the oil pan rails.
  3. Install the main caps in their correct order and torque the bolts in three stages, using the specified torque and angle sequence. For most small-block Chevy applications, the final torque is around 75–85 ft-lb plus an additional angle (consult kit instructions).
  4. Check crankshaft end-play with a feeler gauge. Acceptable range is typically 0.004”–0.008”. Adjust with selective thrust bearings if needed.
  5. Rotate the crank to ensure smooth rotation. Any binding indicates clearance issues.

Preparing the Pistons and Connecting Rods

  • The COMP Cams stroker kit includes pistons, rings, and rods pre-assembled or as separate components. If separate, press the piston pins in using a proper press or have a machine shop do it.
  • File-fit the piston rings according to the instructions. Ring end gap is critical for a stroker engine due to higher cylinder pressures. Typical gap for the top ring is 0.018”–0.022” for street/strip use; second ring slightly larger. Check with a ring squaring tool and feeler gauge.
  • Install the rings on the pistons, stagger the gaps as recommended (usually 120° apart each ring). Lubricate the ring lands lightly.
  • Apply a thin coat of assembly lube to the wrist pins and rod bearings.

Installing the Rod and Piston Assemblies

  1. Oil the cylinder walls with engine oil or assembly lube.
  2. Compress the rings using a ring compressor. Tap the piston into the cylinder with a wooden hammer handle, ensuring the rod aligns with the crank journal.
  3. Install the rod bearings and caps. Torque the rod bolts to spec (often 40–50 ft-lb for typical small block, but follow kit guidelines).
  4. After all pistons are installed, check rod side clearance with a feeler gauge. Typical is 0.010”–0.020”.
  5. Rotate the crankshaft by hand to confirm no binding. If it feels tight, re-check ring gaps and bearing clearances.

Tip: Use Plastigauge on at least one main and one rod bearing to confirm oil clearance. Desired clearance for a performance build is typically 0.002”–0.0025” on mains and 0.002”–0.003” on rods.

Cylinder Heads and Valvetrain

While the stroker kit itself only changes the bottom end, the cylinder heads must be compatible with the new displacement to achieve 400+ hp.

Head Preparation

  • If reusing the original heads, have them disassembled, cleaned, and inspected for cracks. Consider a valve job and port clean-up to improve flow.
  • Many builders choose aftermarket aluminum heads with larger runners (e.g., 180–195 cc intake runners) to exploit the stroker’s increased air demand.
  • Install new valve stem seals and springs that match the camshaft profile (if you are also upgrading the cam).

Head Gasket Selection

Choose a head gasket that matches the new bore size (often 4.030” or 4.060” for SBC 350 blocks stroked to 383 or 400 CID). MLS (multi-layer steel) gaskets are recommended for their clamping force and resistance to detonation. Use a slightly thicker gasket if you need to reduce compression to run pump gas.

Installing the Cylinder Heads

  1. Clean the block deck and head surfaces thoroughly.
  2. Position the head gaskets on the block (check orientation marks).
  3. Place the head on the block and thread in the bolts or head studs. Lubricate the threads and under the bolt heads with oil or ARP assembly lube.
  4. Torque in a specific sequence starting from the center outward. Follow the manufacturer’s torque specs, typically in two or three increments. Example: a common SBC head bolt torque is 65 ft-lb on the first pass, then 75 ft-lb final. Some designs require 65 ft-lb plus a 90° angle.

If you removed the camshaft, now is the time to install the new COMP Cams camshaft and lifters. Lubricate the cam lobes with break-in lube and the lifters. Install the timing chain and gears, aligning the marks precisely.

Timing, Oil System, and Accessories

With the heads and rotating assembly in place, you can address the timing components and oiling system.

Timing Chain Installation

  • Install the double-roller timing set that came with your kit or a separate set. Ensure the crank and cam sprocket marks align at TDC #1 cylinder.
  • Check camshaft end play (0.001”–0.005” typical) by installing the timing cover and button.
  • If you are degreeing the cam (recommended for optimum power), use a degree wheel and dial indicator to verify lobe centerlines. Adjust with offset bushings if needed.

Oil Pump and Pan

  1. Install a new or rebuild the oil pump with a high-volume design if using a stroker kit, as increased bearing clearances and capacity demand more flow.
  2. Position the pickup tube with the correct depth in the pan. Weld or retain it securely.
  3. Apply a thin bead of RTV to the oil pan gasket corners and install the pan. Torque pan bolts lightly (check spec, often 10–12 ft-lb).
  4. Install the harmonic balancer using the proper tool. Do not hammer it on.

Fuel and Ignition Upgrades

With displacement increased, the engine will require more fuel. Stock fuel injectors may be insufficient; upgrade to an injector size that supports 400+ horsepower. Similarly, the stock ignition curve may need adjustment. Install new spark plugs with a heat range appropriate for the compression ratio. Gap them per the cam manufacturer’s recommendation (often 0.035”–0.045”).

Final Assembly and Startup

Reassemble all ancillary components: intake manifold, exhaust, distributor, spark plug wires, sensors, and accessories. Double-check all connections.

Initial Fill and Prime

  1. Fill the engine with break-in oil (high zinc/ZDDP) and install a new filter. Many builders use non-detergent oil for the first few minutes.
  2. Refill the cooling system with a 50/50 mix of distilled water and antifreeze.
  3. Reconnect the battery.
  4. Prime the oil system by removing the distributor and using a drill-driven oil pump priming tool. Spin until oil reaches the rocker arms (if adjustable) or you see pressure on a gauge. This prevents dry start damage.

First Start Procedure

  • Set ignition timing to a safe initial advance (typically 10°–12° BTDC for a street stroker).
  • Start the engine and immediately raise the RPM to 2000–2500 RPM for the first 20 minutes for cam break-in (if a new flat-tappet cam was installed). For roller cams, idle can be used, but still vary RPM to circulate oil.
  • Check for oil leaks, coolant leaks, and any unusual noises. Monitor oil pressure. If it drops below 10 psi at hot idle, investigate immediately.
  • After break-in, shut down and change the oil and filter to remove debris.

    • Road Test and Tuning

    After the first oil change, take the vehicle for a gentle test drive. Gradually increase RPM under load. Listen for detonation. If the engine pings, retard timing or use higher octane fuel. For maximum performance, schedule a chassis dyno tune. A professional tuner can dial in the air/fuel ratio and ignition timing for the combination.

    Helpful resources include the COMP Cams official website for technical documents and Summit Racing for parts and advice. Online forums like LS1Tech or Hotrodders.com have many build threads on stroker installations.

    Conclusion

    Installing a COMP Cams stroker kit is a rewarding way to achieve 400+ horsepower from a small-block engine. The process demands careful attention to clearances, torque specs, and component cleanliness. By following the expanded steps in this guide—including block preparation, ring gapping, bearing clearance checks, and proper break-in—you can build an engine that delivers strong power and long-lasting reliability. Whether you are a seasoned engine builder or an enthusiast taking on the project for the first time, take your time and verify every measurement. The result will be a responsive, torquey engine that transforms your vehicle’s driving experience. If you are unsure about any machining step, consult a professional engine shop. With the right preparation and patience, you can enjoy the thrill of a COMP Cams-powered stroker for years to come.