This procedure replaces the timing chain, sprockets, and related components on a 1966 Chevrolet Corvette 327ci V8 engine to restore proper valve timing and eliminate chain slack.

Warnings

Tools required

Parts

• Timing chain kit (includes chain, cam sprocket, crank sprocket, and typically cam button) × 1 — Use OEM specification or quality aftermarket (Cloyes, Melling)
• Timing cover gasket × 1 — Use OEM specification
• Timing cover seal (front crankshaft seal) × 1 — Use OEM specification
• Harmonic balancer seal (if timing cover is integral seal design) × 1 — Use OEM specification
• Water pump gasket (if applicable - some 327s use sealant) × 1 — Use OEM specification
• Engine oil (5W-30 Conventional) × 1 — Use OEM specification
• Coolant (DEX-COOL Extended Life Orange) × 1 — Use OEM specification
• Camshaft button or thrust plate (if not included in kit) × 1 — Use OEM specification
• RTV silicone gasket maker (for timing cover installation) × 1 — GM 1052942 or equivalent high-temp RTV
• Thread locker (blue - medium strength) × 1 — Loctite 243 or equivalent

Fluids

• 5W-30 Conventional engine oil — 5 qt
• DEX-COOL Extended Life coolant (Orange) — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Allow engine to cool completely (minimum 2 hours after last operation)
4. Drain engine coolant into appropriate container by opening radiator petcock and removing lower radiator hose
5. Drain engine oil and remove oil filter
6. Remove radiator shroud (if equipped) for access clearance
7. Remove upper and lower radiator hoses
8. Remove drive belts (alternator, power steering, air conditioning if equipped)
9. Label and disconnect any wiring or hoses that will interfere with timing cover removal

Procedure

1. 1

   Remove radiator and water pump
   Remove the radiator mounting bolts and carefully lift radiator from engine bay. Remove the 6 water pump mounting bolts and remove water pump from timing cover. The water pump on the 1966 327 is mounted directly to the timing cover and must be removed for timing cover access.
2. 2

   Remove harmonic balancer
   Remove the harmonic balancer center bolt using a 1-1/8" socket. To prevent crankshaft rotation, place transmission in gear (manual) or use a flywheel holding tool at the bellhousing inspection cover. After removing the bolt, install a harmonic balancer puller onto the balancer hub. DO NOT use a jaw-type puller on the outer ring as this can damage the balancer. Tighten the puller center bolt to extract the balancer from the crankshaft snout. The balancer is press-fit and may require substantial force.
3. 3

   Remove timing cover
   Remove the 7 timing cover bolts (4 around perimeter, 2 at bottom, 1 at top center). Carefully pry the timing cover away from the engine block using a flat pry bar at the designated pry points (typically cast into the cover). Do not pry against the oil pan gasket surface. Once free, remove the timing cover and front crankshaft seal as an assembly. Inspect the oil slinger behind the harmonic balancer - it should remain on the crankshaft.
4. 4

   Verify timing mark alignment before disassembly
   Rotate the crankshaft clockwise (viewed from front) until the timing marks on the camshaft sprocket and crankshaft sprocket are aligned and closest together (both dots or lines facing each other at the 6 o'clock and 12 o'clock positions respectively). This is TDC for cylinder #1. Take a photo or make detailed notes of the mark alignment for reference during reassembly. This confirms proper timing before disassembly and serves as a reference point.
5. 5

   Remove camshaft sprocket and timing chain
   Remove the camshaft sprocket bolt (20 ft-lb torque - may require penetrating oil if seized). Use a 9/16" socket or wrench. Once the bolt is removed, the camshaft sprocket and timing chain can be pulled forward off the camshaft and crankshaft. The camshaft sprocket is located on a dowel pin on the camshaft - you may need to gently pry or tap it forward. Remove the timing chain and both sprockets as an assembly. Note the orientation of the crankshaft sprocket - the timing mark faces outward.
6. 6

   Remove crankshaft sprocket and inspect
   If the crankshaft sprocket did not come off with the timing chain, use a gear puller or carefully pry it off the crankshaft. Inspect the crankshaft sprocket, camshaft sprocket, and timing chain for wear. Look for chain elongation (excessive slack), sprocket tooth wear (hooked or pointed teeth), or damage. Inspect the camshaft thrust button (located behind cam sprocket) for excessive wear - replace if worn beyond 0.010" or if grooved. Check camshaft endplay with a dial indicator - specification is 0.004" to 0.012".
7. 7

   Clean timing cover and block surfaces
   Thoroughly clean all gasket mating surfaces on the timing cover and engine block using a gasket scraper and wire brush. Remove all old gasket material, RTV sealant, and debris. Clean the timing cover bolt holes and ensure they are free of coolant or oil. Inspect the timing cover for cracks, especially around bolt holes and water passages. Clean the crankshaft snout and inspect for scoring or damage that could cause seal leakage.
8. 8

   Install new crankshaft sprocket
   Install the new crankshaft sprocket onto the crankshaft with the timing mark facing outward (away from engine block). The sprocket should slide onto the crankshaft snout and seat against the shoulder. Tap gently with a soft mallet if needed - it should be snug but not require excessive force. Verify the sprocket is fully seated and the timing mark is visible and facing forward.
9. 9

   Install new camshaft sprocket and timing chain
   Temporarily install the camshaft sprocket onto the camshaft (without the bolt) to verify the timing mark location. Remove the camshaft sprocket and loop the new timing chain over it, aligning the bright or marked link (or timing mark on chain) with the timing mark on the camshaft sprocket. Install the camshaft sprocket and chain assembly onto the camshaft, engaging the dowel pin in the camshaft. Simultaneously engage the timing chain onto the crankshaft sprocket. Rotate the assembly as needed to align the timing marks: the camshaft sprocket mark should point toward the crankshaft sprocket mark (typically at 6 o'clock on cam sprocket and 12 o'clock on crank sprocket, facing each other). The marks should be on a centerline through both shaft centers.
10. 10

    Verify timing alignment and install camshaft bolt
    With the timing chain installed and both sprockets engaged, verify that the timing marks on the camshaft sprocket and crankshaft sprocket are precisely aligned and facing each other. This is critical - misalignment will cause engine damage. The marks should be closest together, typically with the crank sprocket mark at approximately 12 o'clock and the cam sprocket mark at approximately 6 o'clock. Apply a small amount of blue thread locker to the camshaft sprocket bolt threads, install the bolt, and torque to 20 ft-lb (27 Nm). Recheck timing mark alignment after torquing.
11. 11

    Install new timing cover seal
    Install the new front crankshaft seal into the timing cover. The seal should be driven in squarely using a seal driver or large socket that contacts only the outer edge of the seal (not the inner lip). Drive the seal until it is flush with or slightly below the timing cover surface. Lubricate the seal lip with clean engine oil before installing the timing cover. Inspect the seal installation area in the timing cover for damage or roughness that could cause premature seal failure.
12. 12

    Install timing cover with new gasket
    Apply a thin bead (approximately 1/8" diameter) of RTV silicone gasket maker to the engine block timing cover mating surface, paying particular attention to the area where the timing cover meets the oil pan gasket. If using a pre-cut gasket, install it onto the engine block with a light coating of RTV on both sides. Position the timing cover carefully over the crankshaft snout, ensuring the seal lip is not damaged during installation. Guide the cover into place and start all 7 bolts finger-tight. Torque the timing cover bolts in a cross-pattern to 18 ft-lb. Do not overtighten as the cover is aluminum and bolt holes can strip.
13. 13

    Install harmonic balancer
    Ensure the crankshaft snout and harmonic balancer hub bore are clean and dry. Verify the woodruff key (if equipped) is properly seated in the crankshaft keyway. Align the harmonic balancer keyway with the crankshaft key and slide the balancer onto the crankshaft as far as it will go by hand. Using a harmonic balancer installation tool (threaded installer that threads into the crankshaft and pulls the balancer onto the taper), draw the balancer fully onto the crankshaft until it seats against the timing cover. Do NOT use an impact wrench or hammer to install the balancer. Install the harmonic balancer bolt and torque to 60 ft-lb (81 Nm).
14. 14

    Reinstall water pump
    Install a new water pump gasket (or apply RTV sealant if original design uses sealant) to the timing cover. Position the water pump onto the timing cover and install the 6 water pump bolts. Torque the water pump bolts in a cross-pattern to 30 ft-lb. Reconnect any coolant bypass hoses or heater hoses that attach to the water pump. Ensure all hose clamps are properly tightened.
15. 15

    Reinstall radiator and accessories
    Reinstall the radiator into the engine bay and secure with mounting bolts. Reconnect upper and lower radiator hoses and tighten clamps. Install new drive belts (alternator, power steering, air conditioning if equipped) and adjust to proper tension. Reinstall radiator shroud if equipped. Reconnect all wiring and vacuum hoses that were removed during disassembly. Reconnect negative battery cable.

Reassembly

1. Fill engine with 5 quarts of 5W-30 conventional engine oil and install new oil filter
2. Fill cooling system with 10 quarts of DEX-COOL Extended Life coolant (50/50 mix with distilled water)
3. Before starting engine, rotate crankshaft by hand 2 complete revolutions to verify timing chain is properly installed and there is no binding
4. Check that timing marks return to proper alignment after 2 full rotations
5. Start engine and immediately check for oil pressure on gauge
6. Allow engine to reach operating temperature while monitoring for coolant or oil leaks at timing cover, water pump, and harmonic balancer seal
7. Burp cooling system by opening radiator cap (when cool) and adding coolant as needed to eliminate air pockets
8. Recheck all belt tensions after initial warm-up cycle

Verification

• Verify engine oil pressure is normal (40-60 psi at 2000 RPM when warm) within 10 seconds of startup
• Inspect timing cover, water pump, and harmonic balancer area for any signs of coolant or oil leakage after reaching operating temperature
• Listen for abnormal engine noises - a properly installed timing chain should produce no rattling or slapping sounds at idle or under acceleration
• Use a timing light to verify ignition timing is at factory specification (typically 4-8 degrees BTDC at idle for 1966 327, depending on emissions configuration)
• After 50-100 miles of driving, recheck timing cover bolts, water pump bolts, and harmonic balancer bolt for proper torque retention
• Monitor engine temperature gauge to ensure cooling system is functioning properly with no overheating

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