Why the LS2 with a Stage 2 Cam Deserves Your Attention

The LS-based engine swap has become the gold standard for breathing modern power into classic Chevrolet platforms. Among the LS family, the 6.0L LS2 stands out as a smart choice: it offers a substantial displacement advantage over the ubiquitous 5.3L and 5.7L variants, while still fitting into engine bays originally designed for small-block V8s. When you pair that foundation with a Stage 2 camshaft, you unlock a powerband that pulls hard from idle to redline without sacrificing daily drivability. An upgraded cooling system is not negotiable at this power level — it ensures the engine maintains consistent temperatures under heavy load, preventing detonation and extending component life. This guide takes you through the entire process, from parts selection to the first start, with the torque specs, wiring details, and real-world installation notes that separate a clean swap from a headache.

Parts Selection: What You Actually Need for This Swap

Before you pull a single bolt, assemble everything you need. Nothing kills momentum like a parts run mid-project. Below is the full list, organized by system.

Engine and Drivetrain

  • LS2 long block (preferably from a 2005–2007 Corvette or 2006–2007 Trailblazer SS; cranks and rods are forged in both)
  • Stage 2 camshaft — look for a grind in the 218–224 degree duration range at 0.050-inch lift, with 0.550–0.600-inch valve lift. This keeps vacuum usable for power brakes while delivering a noticeable chop at idle and strong mid-range torque.
  • LS2 timing set — a new LS2 timing chain, damper, and phaser limiter (if retaining VVT; if deleting, a standard LS2 timing cover and chain work)
  • Valve springs — upgraded beehive or dual springs rated for 0.600-inch lift. The stock springs will coil-bind with a Stage 2 cam.
  • Pushrods — hardened 7.400-inch or 7.425-inch pushrods, depending on head milling and lifter preload. Measure pushrod length during assembly.
  • LS7 or aftermarket lifters — the LS7 lifters are a drop-in upgrade that handles higher RPM.
  • Transmission adapter kit — specific to the target transmission (4L60E, 4L80E, T56, TH350, TH400). Each requires a different flexplate, bellhousing spacer, and torque converter pilot.
  • Engine mounts — aftermarket swap mounts designed for your specific Chevy chassis (e.g., Holley, Dirty Dingo, or ICT Billet). These drop the engine lower and farther back than stock frame mounts, improving hood clearance and weight distribution.

Cooling System

  • Radiator — a three-row or four-row aluminum radiator with at least 1.25-inch core tubes. Crossflow designs offer the best heat rejection for tight engine bays.
  • Electric fan(s) — dual 12-inch or single 16-inch high-CFM fan with a shrouded housing. Spal and Derale are proven brands.
  • Thermostat — a 160°F or 180°F high-flow thermostat. Do not bypass the thermostat entirely; the LS coolant flow path needs the restriction to prevent cavitation.
  • Water pump — an LS2-specific aluminum water pump (GM 12562069 or an aftermarket equivalent). The LS2 pump has a reverse-rotation impeller compared to LS1/LS6 pumps, so match the pump to the engine generation.
  • Upper and lower radiator hoses — flexible silicone hoses in 1.5-inch ID, or molded hodes from a donor vehicle that match your radiator ports.
  • Coolant crossover pipe — if converting from a truck intake to a car intake, you may need a crossover pipe to route coolant across the front of the engine.
  • Overflow tank — a universal aluminum tank with a 3/8-inch barb fitting.

Fuel and Electrical

  • LS swap wiring harness — a standalone harness from PSI, BP Automotive, or a similar builder. Ensure it is configured for your specific engine (LS2, 58X crank reluctor, 24X is different).
  • Fuel pump — an in-tank pump with a minimum flow rate of 255 LPH. The Walbro 255 is the standard, but a DW400 or AEM 340 is better if you plan for 500+ hp later.
  • Fuel line kit — 3/8-inch stainless or PTFE line with AN-6 fittings. Avoid rubber hose on the pressure side; ethanol in modern fuels will degrade standard rubber.
  • Fuel pressure regulator — a return-style regulator (Aeromotive 13106 or equivalent) set to 58 psi for returnless systems, or 43 psi for return systems.
  • ECU — the original LS2 ECU (E38 or E67 depending on year) or a Holley Terminator X system for a simpler install. The Holley system eliminates VATS and allows self-tuning.
  • O2 sensors and mass airflow sensor — wideband O2 sensors (Bosch 17025) and an LS3-style MAF sensor for accurate fuel metering.
  • Gauges — an aftermarket gauge cluster or a conversion module to drive the original Chevy gauges from the LS ECU signals. Dakota Digital makes plug-and-play options for many classic Chevy models.

Tools and Safety Equipment

  • Engine hoist with leveler (1-ton capacity minimum)
  • Engine stand (1,000-pound capacity)
  • Torque wrench (ft-lb and in-lb ranges)
  • Tap and die set for cleaning threads
  • Defacing kit for removing old gasket material
  • Dielectric grease for all electrical connections
  • Safety glasses, mechanics gloves, and fire extinguisher (rated for Class B and C)

Preparation: Setting Your Workspace and Vehicle Up for Success

A clean, well-lit workspace with adequate clearance around the vehicle saves hours of frustration. The vehicle should be on jack stands rated for the full vehicle weight, with the wheels chocked and the battery disconnected at the negative terminal. Drain the coolant, engine oil, and transmission fluid before disconnecting any lines. Capture all fluids in approved containers and dispose of them properly.

Removing the Old Engine

Lower the front of the vehicle for access if necessary — many classic Chevy platforms benefit from removing the front bumper, grille, and core support. This gives direct access to the radiator, condenser, and front engine mounts.

  1. Disconnect the battery — both terminals, negative first. Remove the battery box if it obstructs the engine bay.
  2. Drain the cooling system — open the radiator petcock and remove the lower hose to fully drain the block. LS engines have coolant drain plugs on each side of the block; remove these to empty the block completely.
  3. Disconnect all coolant hoses — upper, lower, and heater core hoses.
  4. Remove the radiator and fan assembly — unbolt the fan shroud and radiator brackets. In many classic Chevys, the radiator must come out before the engine to avoid damage.
  5. Mark and disconnect the wiring harness — label every connector with masking tape and a marker. Take photos of the original harness routing before disassembly.
  6. Disconnect the fuel lines — relieve fuel pressure at the fuel rail test port or by pulling the fuel pump relay and running the engine until it stalls. Cap the lines immediately to prevent fuel spillage.
  7. Disconnect the exhaust manifolds — unbolt the exhaust pipes from the manifolds and support the exhaust system with a jack stand if necessary.
  8. Remove the driveshaft — mark the phasing of the driveline components with a paint marker to maintain balance. Slide the driveshaft out of the transmission and secure it with zip ties to the underbody.
  9. Disconnect the transmission — remove the starter, torque converter bolts (access through the starter opening), and transmission-to-engine bolts. Support the transmission with a transmission jack or a sturdy floor jack with a wood block.
  10. Unbolt the engine mounts — support the engine with the hoist and leveler, then remove the mount bolts from the frame side. Carefully lift the engine and transmission assembly as one unit if you plan to reuse the transmission, or separate them first.
  11. Lift the engine out — tilt the engine at a 30–40 degree angle to clear the radiator core support and firewall. Guide it with a spotter on each side to avoid snagging components.

Prepping the LS2 Engine for Installation

Now that the old engine is out, inspect and prep the LS2 on an engine stand. This is the time to address modifications that require engine-out access.

  • Remove the oil pan — on a truck-style LS2 (Trailblazer SS), the oil pan has a rear sump that may interfere with the front crossmember or steering rack. Swap to a car-style oil pan (GM 12570427) with a front sump if necessary. Replace the oil pan gasket and use a load-limiting torque wrench — the new gasket is metal-rubber composite and requires 18 ft-lb on the M6 bolts in a specific sequence.
  • Install the Stage 2 camshaft — lubricate the cam lobes and journals with high-zinc assembly lube. Slide the cam into the block gently, rotating it as you push to engage the distributor drive gear (or cam position sensor reluctor). Torque the cam retainer bolts to 8 ft-lb. If the cam has a smaller base circle, you must check pushrod length.
  • Upgrade the valve springs — remove the rocker arms, pushrods, and valve springs using a valve spring compressor. Install springs matched to the cam's lift and RPM range. Set installed height to manufacturer specification (typically 1.800 inch ± 0.015 inch). Check for coil bind at full lift by rotating the engine over and measuring clearance.
  • Replace the timing chain — remove the front cover, timing chain, and sprockets. Install a new LS2 chain and sprockets with the timing marks aligned at top dead center (TDC). Torque the crankshaft sprocket bolt to 260 ft-lb — use a crankshaft holding tool to prevent rotation. Apply thread locker to the bolt before final torque.
  • Reassemble the front cover — clean the sealing surfaces and apply a small bead of anaerobic sealant (Permatex 51813) to the front cover. Torque the M6 bolts to 18 ft-lb and the M8 bolts to 30 ft-lb. Install a new crankshaft front seal and harmonic balancer. Torque the balancer bolt to 260 ft-lb.
  • Install new spark plugs — use NGK TR55 or equivalent, gapped to 0.040 inch for naturally aspirated applications. Coat the threads lightly with anti-seize.
  • Check coolant passages — blow compressed air through the block, heads, and water pump passages to remove any debris. The LS2 has a steam crossover tube at the back of the heads; ensure it is properly routed to the radiator or coolant reservoir. If block-off plugs are present, remove them for cooling system flow.
  • Install intake and exhaust gaskets — use GM MLS intake gaskets (only available from GM; aftermarket copies leak) and Fel-Pro exhaust gaskets. Apply a thin layer of copper spray to the exhaust gaskets for better sealing.

Installing the LS2 Engine with Stage 2 Cam

With the engine prepped, it's time to mate the transmission and lower the LS2 into the bay. This is a two-person job at minimum.

Mating the Transmission

If you are reusing the original transmission, you need an adapter plate and a flexplate spacer. The LS2 has a different crank flange pattern than the older small-block. Install the flexplate (for an automatic) or flywheel (for a manual) before the transmission is in the car.

  1. For automatic transmissions — attach the flexplate to the crankshaft flange using the new bolts (ARP 134-6001) torqued to 75 ft-lb. Install the torque converter onto the transmission input shaft before mating the transmission to the engine. The converter should slide all the way onto the pump spline — you will feel it engage past two distinct detents. Rotate the converter until the bolt holes align with the flexplate.
  2. For manual transmissions — attach the flywheel and clutch assembly (LS2-specific pressure plate, 8-bolt pattern). Torque the flywheel bolts to 75 ft-lb with thread locker. Install the pilot bearing in the crankshaft recess. Use a clutch alignment tool to center the clutch disc before bolting the pressure plate to 45 ft-lb in a star pattern.
  3. Bolting the transmission to the engine — lift the transmission into position and align the input shaft with the pilot bearing or torque converter. Apply anti-seize to the bellhousing bolts and torque them to 37 ft-lb. The LS2 block has metric M12 threads at the top and M10 threads at the bottom — use the correct bolts for each location.

Dropping the Engine In

Lower the engine/transmission assembly into the engine bay with the engine leveler and hoist. The process goes faster if you have a spotter watching clearance at the firewall, frame rails, and steering shaft.

  • Install engine mounts to the LS2 block first — torque the block-side bolts to 37 ft-lb. Use the aftermarket swap mounts designed for your chassis. Most swap mounts index the engine lower and 1–2 inches rearward of the original small-block position.
  • Lower the assembly slowly — angle the engine downward at the front to clear the cowl, then level it as it drops into position. The LS2 is wider than the original inline-six or small-block, so watch clearance at the frame rails and steering box. In many applications, the frame rails need notching or a plate reinforcement.
  • Bolt the engine mounts to the frame — once the engine is sitting on the mounts, loosely bolt the mount saddles to the frame. Torque them to 50 ft-lb for polyurethane mounts or 37 ft-lb for rubber mounts. Poly mounts transmit more vibration but provide more stable cam timing retention.
  • Reconnect the transmission mount — install the transmission crossmember and torque the mount to 50 ft-lb. The transmission should be level with the engine; adjust the engine angle with the mounts if needed.
  • Install the driveshaft — apply lithium grease to the slip yoke splines and slide it into the transmission. Bolt the driveshaft to the rear differential flange with new bolts torqued to 50 ft-lb.
  • Reinstall the starter — the LS2 starter mounts to the right side of the block. Tighten the two bolts to 37 ft-lb. If you retain the original GM starter, replace the solenoid wire with a heat-resistant sleeve.

Cooling System: Build for Heat Dissipation

A Stage 2 cam increases cylinder pressure and thermal load significantly. The stock LS2 cooling system was designed for ~400 hp. At 450–550 hp, you need additional capacity.

Radiator and Fan Setup

  • Radiator choice — an all-aluminum radiator with at least two 1.25-inch core rows. A crossflow design reduces pressure drop across the core and fits better in narrow engine bays. Champion, Cold Case, and C&R Racing make direct-fit options for many classic Chevys.
  • Electric fan installation — dual 12-inch fans with a combined draw of 25–30 amps provide adequate airflow at idle and low speed. Use a DC fan controller (e.g., Spal PWM controller or a simple thermostatic switch with a relay). Set the fan on temperature to 195°F and off at 185°F. Wire the fan power through a 40-amp relay, and fuse the circuit at 30 amps per fan.
  • Hose routing — the LS2 lower radiator hose has a molded curve that turns backward toward the passenger side. If your radiator outlet is on the driver side, use a 90-degree silicone coupler and a short hose section to bridge the gap. Secure all hoses with constant-tension spring clamps; worm-gear clamps can distort rubber hose necks over time.

Coolant Flow Path

The LS2, like all Gen IV LS engines, uses a reverse-flow cooling path: coolant enters the heads first and then flows through the block. The steam crossover at the back of the heads must have unrestricted flow to the radiator's top tank or the coolant reservoir. If you block this line, the rear cylinders will overheat.

  • Install a steam line kit from the rear crossover to the radiator upper hose or a dedicated port on the thermostat housing. Use 5/16-inch heater hose with barb fittings.
  • Use a high-flow 160°F or 180°F thermostat — the flow rate at the thermostat opening should be at least 30 gallons per minute at 3,000 RPM. Stewart Components and Moroso offer high-flow thermostats that meet this spec.
  • Fill the system with Evans Waterless Coolant or a 70/30 mix of deionized water and antifreeze (70% water for better heat transfer, 30% antifreeze for corrosion protection and boil-over prevention). Add a bottle of Water Wetter for maximum surface tension reduction.

Wiring and Fuel System: Making Everything Talk

The LS2 uses a 58X crank reluctor (24X on 2005–2006 engines) and a 4X cam sensor. The wiring harness must be compatible with your ECU choice.

Harness Installation

  • Standalone harness — run the harness through the engine bay, securing it with zip ties every 6 inches. Route the harness away from heat sources (exhaust manifolds, crossover pipe).
  • ECU mounting — mount the ECU inside the cabin on the firewall or under the dash, away from direct heat and moisture. Protect the connector with dielectric grease and secure the harness with a grommet at the firewall pass-through.
  • VATS and anti-theft — if using the original GM ECU, you must tune out VATS or buy a VATS bypass module. The Holley Terminator X does not require any anti-theft modification.
  • Gauge interfacing — the LS2 sends engine speed, coolant temperature, oil pressure, and speedometer signals via CAN bus. Many aftermarket clusters (Dakota Digital, Intellitronix) directly read the LS2 CAN bus. For analog gauges, you need a signal converter (example: a Dakota Digital GM-LS adapter).

Fuel System Setup

The LS2 requires 58 psi at the fuel rail for returnless systems or 43 psi for return-type systems. Install a new fuel pump in the tank or an inline pump mounted on the frame rail near the tank.

  • Fuel pump wiring — use a dedicated 30-amp circuit with a relay triggered by the ECU's fuel pump output. The pump should prime for 2 seconds when the ignition is turned on, then run continuously after the engine starts.
  • Fuel line routing — use AN-6 feed and AN-4 return lines. Route the lines along the frame rail, away from the exhaust. Secure them with nylon clamps every 12 inches. Use a PTFE hose with stainless braid for maximum ethanol compatibility.
  • Fuel pressure regulator — if using a return-style system, mount the regulator near the fuel rail and run a return line back to the tank. Set the pressure to 43 psi with the engine running and vacuum reference line attached (to maintain constant flow across the injectors).

Exhaust and Tuning Considerations

A Stage 2 cam requires a free-flowing exhaust to reach its full potential. Use 1.75-inch to 1.875-inch primary tubes with a 3-inch collector for naturally aspirated LS2 builds. Headers designed specifically for LS swaps are available from Hooker, Holley, and Stainless Works for most Chevy chassis.

After the exhaust is installed, the engine must be tuned. A mail-order tune that accounts for the cam timing, injector data, throttle follower, and idle air control is essential for consistent drivability. If using the Holley Terminator X system, the self-learning mode can create a base fuel table, but a dyno tune or remote calibration from an experienced LS tuner will extract the maximum power and smooth out the idle.

First Start, Break-In, and Test Drive

After double-checking all connections, fluid levels, and bolt torque, reinstall the battery and prime the fuel system by cycling the key three times (without starting) to purge air from the fuel lines. Turn the engine over with the ignition coil harness disconnected to build oil pressure before the first start. Once oil pressure registers on the gauge, reconnect the coils and start the engine. Let it idle for 15 minutes at 2,000 RPM for the camshaft break-in (flat-tappet cams require 20 minutes at varying RPM; roller cams like the Stage 2 cam require a shorter break-in but still benefit from load cycling).

Check for leaks at every seam: gaskets, hoses, drain plugs, and radiator. Test the cooling fan operation by letting the engine reach operating temperature and confirming the fan cycles on and off. Take the vehicle on a 10-mile test drive, keeping the engine speed under 3,000 RPM and varying the throttle position to seat the piston rings. After the drive, check the oil and coolant levels and re-torque the intake bolts to 18 ft-lb and the exhaust manifold bolts to 18 ft-lb after the engine cools.

Common Pitfalls and How to Avoid Them

  • Oil pan clearance — the truck-style LS2 pan hits most Chevy crossmembers. Always test-fit the pan against the car's chassis before installation.
  • Wiring harness length — many standalone harnesses are built for specific engine bays. If your Chevy has a long engine bay (e.g., 1965 Impala), the harness may be short. Order a harness 12 inches longer than your measured distance from the ECU to the frontmost sensor.
  • Thermostat position — the LS2 thermostat is located at the front of the intake. If your radiator cap is on the driver side, you may need a remote thermostat housing to maintain flow direction.
  • Steam line kinking — use a 5/16-inch steel tube or nylon hose for the steam line to prevent kinking near the firewall.
  • Radiator cap pressure — use a 15 psi cap for an aluminum radiator and 20 psi for a copper/brass radiator. A higher-pressure cap raises the boiling point but stresses the core.

Performance Outcomes: What to Expect

With the LS2, Stage 2 cam, and upgraded cooling system properly installed and tuned, a classic Chevy will produce between 420 and 480 rear-wheel horsepower on pump gas. Torque will exceed 400 lb-ft from 2,800 RPM to 6,200 RPM. The cooling system, if built to the specifications above, will maintain coolant temperatures within 190–210°F even during extended high-RPM operation in warm weather. The swap adds minimal weight compared to the original iron small-block — the all-aluminum LS2 weighs approximately 400 pounds fully dressed, which is 40–60 pounds lighter than most iron V8s, improving both acceleration and handling.

When you hit the throttle and feel the cam come on the cam, you will understand why the LS swap is the dominant engine conversion in the classic car community. The Stage 2 cam gives you that aggressive idle tone and mid-range punch, the LS2 delivers effortless torque, and the cooling system keeps everything in the temperature range that promotes long engine life. This is a build that respects the classic Chevy heritage while delivering modern performance you can drive every day.

For further reading on LS swap fundamentals, consult the Holley LS Swap Guide and the Super Chevy LS Swap Reference. For cooling system design details, Stewart Components' technical page on water pump flow is an excellent resource.