This procedure covers removal and replacement of the timing chain guide(s) on the 1966 Chevrolet Corvette 327ci V8, requiring removal of the timing cover, timing chain, and associated components.

Warnings

Tools required

Parts

• Timing chain guide × 1 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Timing cover seal × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Harmonic balancer bolt × 1 — Use OEM specification
• Timing chain (if worn) × 1 — Use OEM specification
• Timing chain gear set (if worn) × 1 — Use OEM specification
• Water pump gasket × 1 — Use OEM specification

Fluids

• 5W-30 Conventional Engine Oil — 5 qt
• DEX-COOL Extended Life Coolant (Orange) — 10 qt

Preparation

1. Park vehicle on level surface and allow engine to cool completely (minimum 2 hours)
2. Disconnect negative battery cable
3. Drain engine coolant into appropriate container by opening radiator petcock and removing radiator cap
4. Drain engine oil into drain pan by removing oil pan drain plug
5. Remove air cleaner assembly and set aside
6. Label and disconnect all vacuum lines, electrical connectors, and linkages from carburetor and distributor
7. Remove distributor cap and mark distributor rotor position relative to distributor housing for reinstallation reference

Procedure

1. 1

   Remove radiator and fan assembly
   Remove upper and lower radiator hoses from radiator. Disconnect transmission cooler lines if equipped with automatic transmission. Remove radiator mounting bolts and lift radiator out of vehicle. Remove fan shroud if equipped. Remove 4 fan blade bolts and remove fan assembly from water pump. Remove fan belt(s) from pulleys.
2. 2

   Remove water pump
   Remove water pump pulley bolts while holding pulley stationary. Remove the 5 water pump mounting bolts and carefully pry water pump away from timing cover. Remove and discard old water pump gasket.
3. 3

   Remove harmonic balancer
   Remove the single center bolt from harmonic balancer using breaker bar (turn counterclockwise). Install harmonic balancer puller onto balancer hub with bolts threaded into the tapped holes in the balancer face. Tighten puller center bolt to draw balancer off crankshaft snout. Do not hammer on balancer or use jaw-type pullers that grip the outer ring, as this will damage the balancer.
4. 4

   Remove timing cover
   Remove crankshaft pulley if still attached. Remove the 2 oil pan-to-timing cover bolts from bottom of timing cover. Remove the 8 timing cover mounting bolts around perimeter of cover. Carefully pry timing cover away from engine block using flat-blade screwdriver at pry points. Remove timing cover and discard old gasket and front seal.
5. 5

   Verify and mark timing alignment
   Rotate crankshaft until timing marks on crankshaft sprocket and camshaft sprocket are aligned and facing each other (both marks should point toward each other with timing chain between them). This is the number 1 cylinder TDC position. Mark this position with paint pen or scribe for reference. Take a photograph if possible.
6. 6

   Remove camshaft sprocket and timing chain
   Remove the 3 camshaft sprocket bolts (two bolts plus center distributor drive gear bolt on early 327). Note that camshaft sprocket is located on camshaft by a dowel pin. Carefully pull camshaft sprocket forward along with timing chain off camshaft. If sprocket is tight, use two small pry bars on either side to walk it forward evenly. Do not pry against camshaft directly.
7. 7

   Remove crankshaft sprocket
   Pull crankshaft sprocket straight off crankshaft using two pry bars or sprocket puller. The sprocket should slide off with hand pressure or light prying. If stuck, tap gently from behind with soft mallet while supporting sprocket.
8. 8

   Remove and inspect timing chain guide
   Remove the timing chain guide mounting bolt located on engine block. Remove the worn timing chain guide. Inspect guide for cracks, excessive wear grooves, or broken sections. Inspect timing chain for elongation (more than 0.5 inch stretch over 12-inch span indicates replacement needed). Inspect sprockets for hooked or worn teeth.
9. 9

   Clean all mating surfaces
   Use gasket scraper to remove all old gasket material from timing cover mating surface on engine block and from oil pan rail where timing cover meets oil pan. Clean crankshaft snout and remove any burrs. Wire brush and clean all bolt holes. Wipe all surfaces with brake cleaner and allow to dry completely.
10. 10

    Install new timing chain guide
    Position new timing chain guide in location on engine block. Install guide mounting bolt and tighten securely. Verify guide is properly seated and does not interfere with crankshaft sprocket area.
11. 11

    Install crankshaft sprocket
    Install crankshaft sprocket onto crankshaft with timing mark facing outward. Slide sprocket onto crankshaft until it seats fully against crankshaft shoulder. Sprocket should slide on with hand pressure; if tight, tap gently with soft mallet on sprocket hub only (not outer teeth).
12. 12

    Install timing chain and camshaft sprocket
    Loop timing chain around crankshaft sprocket. Hold camshaft sprocket with timing chain engaged on sprocket teeth and position assembly so that timing marks on both sprockets align facing each other when sprocket is slid onto camshaft. Align camshaft sprocket with dowel pin on camshaft and slide sprocket onto camshaft. Verify timing marks are properly aligned with both marks pointing toward each other.
13. 13

    Secure camshaft sprocket
    Install the camshaft sprocket mounting bolts (3 bolts total including center distributor drive gear bolt if equipped). Apply thread sealer to bolt threads. Tighten bolts evenly in progressive pattern to secure sprocket to camshaft.
14. 14

    Verify timing chain tension and alignment
    Rotate crankshaft two complete revolutions clockwise (viewed from front) and verify timing marks return to aligned position. Check timing chain for proper tension; there should be minimal slack on tight side of chain. Verify new timing chain guide is making proper contact with chain and not interfering with rotation.
15. 15

    Install new timing cover seal and gasket
    Install new front crankshaft seal into timing cover by pressing evenly until flush with cover surface (seal lip should face inward toward engine). Apply thin bead of RTV silicone to oil pan rail where timing cover meets oil pan (both sides). Position new timing cover gasket onto engine block, aligning all bolt holes. Apply small amount of grease to seal lip to ease installation over crankshaft snout.
16. 16

    Install timing cover
    Carefully slide timing cover over crankshaft snout, guiding seal over crankshaft. Align timing cover with dowel pins on engine block. Install the 8 timing cover mounting bolts and the 2 oil pan-to-timing cover bolts. Apply thread sealer to bolts that thread into water passages. Tighten all bolts in crisscross pattern progressively.
17. 17

    Install harmonic balancer
    Clean harmonic balancer hub and apply small amount of engine oil to crankshaft snout and balancer hub bore. Align balancer keyway with crankshaft key and slide balancer onto crankshaft as far as it will go by hand. Install new harmonic balancer bolt with washer and tighten to draw balancer fully onto crankshaft. Ensure balancer is fully seated against crankshaft shoulder.
18. 18

    Install water pump
    Install new water pump gasket on timing cover. Position water pump onto timing cover and install the 5 water pump mounting bolts. Apply thread sealer to bolts threading into water passages. Tighten bolts evenly in crisscross pattern. Install water pump pulley and tighten pulley bolts.

Reassembly

1. Install fan belt(s) and adjust to proper tension (approximately 1/2 inch deflection with moderate thumb pressure)
2. Install fan assembly to water pump with 4 bolts
3. Install fan shroud if equipped
4. Install radiator and connect mounting hardware
5. Connect upper and lower radiator hoses with new clamps
6. Connect transmission cooler lines if equipped
7. Reinstall distributor cap and all vacuum lines, ensuring rotor position matches original mark
8. Reconnect all electrical connections and throttle linkage
9. Install air cleaner assembly
10. Reconnect negative battery cable
11. Refill cooling system with 10 quarts DEX-COOL coolant (50/50 mix with distilled water)
12. Refill engine with 5 quarts 5W-30 conventional engine oil
13. Prime oil system by cranking engine with coil wire disconnected until oil pressure registers

Verification

• Start engine and verify no coolant or oil leaks from timing cover, water pump, or oil pan areas
• Verify engine runs smoothly without unusual noises from timing chain area
• Check ignition timing with timing light and adjust distributor if necessary to match specification (typically 4-8 degrees BTDC at idle for 1966 327)
• Allow engine to reach normal operating temperature and verify cooling system operation
• Recheck all fluid levels after test drive
• Listen for any timing chain slap or rattling noises during idle and acceleration, which would indicate improper installation
• After 500 miles, recheck harmonic balancer bolt torque and all timing cover bolts for proper retention

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