Remove and replace the harmonic balancer (crankshaft damper) on a 1966 Chevrolet Corvette 327ci V8 engine to restore proper crankshaft vibration damping and prevent accessory drive belt misalignment.

Warnings

Tools required

Parts

• Harmonic balancer/crankshaft damper × 1 — Use OEM specification for 327ci with correct balance factor
• Crankshaft balancer bolt × 1 — Use OEM specification - reuse if condition permits
• Crankshaft balancer washer × 1 — Use OEM specification
• Fan belts (V-belts) × 2 — Replace if worn or frayed

Preparation

1. Park vehicle on level ground and apply parking brake
2. Disconnect negative battery cable to prevent accidental starter engagement
3. Allow engine to cool completely if recently operated
4. Raise front of vehicle with floor jack and support securely on jack stands
5. Remove radiator fan shroud if equipped (4 bolts) to provide clearance
6. Mark the position of the timing tab on the timing cover for reference
7. Take a reference photo of the current harmonic balancer timing mark orientation for reassembly verification

Procedure

1. 1

   Remove accessory drive belts
   Loosen the alternator adjustment bolt and pivot bolt, then push the alternator toward the engine block to create slack in the belt. Remove the alternator belt. If equipped with power steering or air conditioning, loosen the respective component mounting bolts and remove those belts as well. The 1966 Corvette 327 typically uses 2 V-belts for the water pump/alternator and power steering pump.
2. 2

   Access the crankshaft balancer bolt
   Working from underneath the vehicle or through the front of the engine bay, locate the large center bolt securing the harmonic balancer to the crankshaft. Clean any dirt or debris from around the bolt and balancer face using a wire brush. Inspect the balancer for visible damage, cracks in the rubber ring, or separation between the outer ring and hub.
3. 3

   Prevent crankshaft rotation
   Use a large pry bar or breaker bar wedged against a strong point on the engine block and a tooth on the starter ring gear (accessed through the bellhousing inspection cover) to prevent the crankshaft from rotating. Alternatively, remove the starter and use a flywheel holding tool. Do not attempt to remove the balancer bolt without preventing rotation, as extreme torque is required.
4. 4

   Remove crankshaft balancer bolt
   Using the appropriate crankshaft bolt socket and a large breaker bar or impact wrench, remove the crankshaft balancer center bolt by turning counterclockwise. This bolt is typically torqued to approximately 60 ft-lbs and may require significant force to break loose. Remove the washer behind the bolt and set both aside. Note the direction and any spacing washers present.
5. 5

   Install harmonic balancer puller
   Thread a harmonic balancer puller onto the balancer hub using the two or three threaded holes in the face of the balancer. The small-block balancer typically has threaded puller holes in the face; verify the exact count and thread size against your specific balancer before selecting a puller. Ensure the puller jaws or bolts are fully threaded and seated evenly. The puller center bolt should contact the end of the crankshaft snout squarely.
6. 6

   Remove harmonic balancer
   Tighten the center bolt of the harmonic balancer puller while holding the puller body steady. Apply steady, even pressure. The balancer will gradually pull off the crankshaft snout. Do not use excessive force or impact tools on the puller center bolt. Once the balancer breaks free, continue turning the puller bolt until the balancer can be removed completely. Remove the puller and set the old balancer aside.
7. 7

   Inspect crankshaft snout and keyway
   Clean the crankshaft snout thoroughly with a clean rag, removing any oil, dirt, or old gasket material. Inspect the keyway in the crankshaft for damage, burrs, or wear. The Woodruff key should be seated flush in its slot and not protruding or damaged. Check the snout surface for scoring, burrs, or damage that could prevent proper balancer installation. If the key is damaged or loose, remove and replace it.
8. 8

   Prepare new harmonic balancer
   Verify the replacement harmonic balancer matches the original in diameter, timing mark position, and keyway orientation. The 1966 327 balancer should have a timing mark notch or groove on the outer ring aligned with TDC. Clean the inner bore of the new balancer with a clean rag. Apply a thin film of clean engine oil to the crankshaft snout and the inner bore of the balancer to ease installation.
9. 9

   Install harmonic balancer installation tool
   Thread the harmonic balancer installation tool into the center of the crankshaft snout. This tool uses the crankshaft's threaded center hole to pull the balancer onto the snout evenly. Ensure the tool is fully threaded and seated squarely. Position the new harmonic balancer onto the crankshaft snout, aligning the keyway in the balancer hub with the Woodruff key in the crankshaft.
10. 10

    Pull balancer onto crankshaft
    Tighten the installation tool center bolt gradually and evenly, pulling the harmonic balancer onto the crankshaft snout. The balancer should slide on smoothly with steady pressure. If excessive resistance is encountered, stop and verify keyway alignment and snout cleanliness. Continue pulling the balancer until it is fully seated against the crankshaft timing gear or front face of the crankshaft. The balancer should seat flush with no gap visible.
11. 11

    Remove installation tool and install balancer bolt
    Remove the harmonic balancer installation tool from the crankshaft. Install the crankshaft balancer washer (if equipped) with the correct orientation, followed by the crankshaft balancer bolt. Hand-thread the bolt several turns to ensure proper thread engagement. Do not force or cross-thread the bolt.
12. 12

    Torque crankshaft balancer bolt
    Using the same method to prevent crankshaft rotation as during removal, torque the crankshaft balancer bolt to approximately 60 ft-lbs (verify against the factory specification) using a calibrated torque wrench. Apply torque in a smooth, steady motion without impact. Verify the balancer is fully seated and does not wobble or have any gap at the crankshaft interface.
13. 13

    Verify timing mark alignment
    Rotate the crankshaft by hand (using a socket on the balancer bolt) and verify the timing mark on the harmonic balancer aligns correctly with the timing tab pointer at TDC (0 degrees). The mark should align precisely when cylinder #1 is at top dead center on the compression stroke. If the mark does not align with your reference photo from preparation, investigate potential installation issues.
14. 14

    Reinstall accessory drive belts
    Route the accessory drive belts around the harmonic balancer, water pump pulley, alternator pulley, and any other accessory pulleys in the correct configuration. Adjust each component (alternator, power steering pump) outward to create proper belt tension. The belt should have approximately 1/2 inch of deflection when pressed firmly at the midpoint of the longest span. Tighten all adjustment and pivot bolts securely.

Reassembly

1. Reinstall the radiator fan shroud if it was removed (4 bolts)
2. Reinstall the starter motor if it was removed for flywheel access (2 bolts)
3. Reinstall the bellhousing inspection cover if it was removed
4. Reconnect the negative battery cable
5. Lower the vehicle from jack stands to the ground

Verification

• Start the engine and verify no unusual vibration at idle or during acceleration
• Check that all accessory drive belts are tracking properly on the harmonic balancer pulley without walking or slipping
• Verify the timing mark remains steady and aligned with the timing tab at idle (use a timing light if available)
• Inspect the harmonic balancer bolt for proper tightness after the first 50-100 miles of operation
• Listen for any unusual noises from the front of the engine that could indicate balancer wobble or misalignment

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