Cylinder Head R&R

Complete removal and reinstallation of cylinder heads on a 1966 Chevrolet Corvette 327ci V8, including disassembly of valve train, intake and exhaust manifolds, and all related components.

Warnings

Tools required

Parts

• Cylinder head gasket set × 1 — Use OEM specification
• Intake manifold gasket set × 1 — Use OEM specification
• Exhaust manifold gaskets × 2 — Use OEM specification
• Valve cover gaskets × 2 — Use OEM specification
• Cylinder head bolts (if reusing, inspect for stretch) × 34 — Use OEM specification
• Valve stem seals (if servicing valves) × 16 — Use OEM specification
• Thermostat housing gasket × 1 — Use OEM specification
• Water outlet gasket × 1 — Use OEM specification

Fluids

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

Preparation

1. Ensure engine is completely cool to the touch
2. Disconnect negative battery cable
3. Drain coolant completely from radiator and engine block drain plugs into appropriate container
4. Drain engine oil if heads are being removed for gasket replacement or resurfacing
5. Remove air cleaner assembly and all hoses/linkages from carburetor
6. Label and photograph all vacuum lines, electrical connections, and hose routing for reassembly reference
7. Place drain pans under work area to catch residual coolant

Procedure

1. 1

   Remove Valve Covers
   Remove the 6 valve cover bolts from each valve cover. Carefully lift valve covers off. If stuck, gently tap with rubber mallet. Remove and discard valve cover gaskets. Inspect valve train for obvious damage or wear.
2. 2

   Remove Intake Manifold
   Disconnect fuel line at carburetor and plug to prevent fuel spillage. Disconnect throttle linkage, choke cable, and all vacuum lines from carburetor and intake manifold. Remove distributor cap and mark distributor position relative to block. Remove distributor hold-down and remove distributor (note rotor position). Remove the 12 intake manifold bolts working from the ends toward the center. Lift intake manifold straight up and off. Remove and discard intake manifold gaskets and end seals.
3. 3

   Remove Exhaust Manifolds
   Working from underneath or engine bay (depending on accessibility), disconnect exhaust pipes from exhaust manifolds at the flange. Remove the 5 bolts securing each exhaust manifold to the cylinder head. Remove exhaust manifolds and set aside. Discard exhaust manifold gaskets.
4. 4

   Remove Rocker Arms and Pushrods
   Loosen each rocker arm stud nut while holding the rocker arm to prevent it from spinning. Remove rocker arm stud nuts, rocker arm balls, and rocker arms. Keep each rocker assembly together if reusing. Lift out all 16 pushrods and place them in order (use a numbered holder or cardboard template). Inspect pushrod ends for wear; replace if worn or bent.
5. 5

   Disconnect Remaining Cylinder Head Components
   Disconnect heater hoses from water outlet/thermostat housing. Remove alternator brackets, power steering pump brackets, or any other accessories still attached to cylinder heads. Remove spark plugs from all cylinders to prevent damage during removal. Remove temperature sender from cylinder head if equipped.
6. 6

   Remove Cylinder Head Bolts
   Using a breaker bar and appropriate socket, loosen all 17 cylinder head bolts on each head in reverse order of the tightening sequence (working from the ends toward the center in a crisscross pattern). Remove all bolts and keep them organized by position. Inspect bolt threads and shanks for necking, stretching, or damage.
7. 7

   Remove Cylinder Heads
   Carefully lift each cylinder head straight up off the engine block. If head is stuck to block, gently pry at a designated pry point (typically near a corner, not between sealing surfaces). Never pry between head and block sealing surfaces. Place cylinder heads on clean workbench with combustion chamber side up. Remove and discard cylinder head gaskets from block deck.
8. 8

   Clean and Inspect Mating Surfaces
   Using a gasket scraper and wire brush, thoroughly clean all gasket material from cylinder head mating surfaces and engine block deck. Do not gouge or scratch sealing surfaces. Clean all coolant and oil passages. Inspect block deck and cylinder head surfaces for warpage using a straightedge and feeler gauge. Maximum allowable warpage is 0.003 inches across the entire surface. If warpage exceeds specification, heads must be resurfaced by a machine shop.
9. 9

   Service Cylinder Heads (if required)
   If cylinder heads require valve service, resurfacing, or other machine work, complete all machine shop operations before proceeding. Ensure all valve seats are properly cut, valves are lapped, valve guides are in specification, and springs are within specification. Replace valve stem seals during valve service.
10. 10

    Install New Cylinder Head Gaskets
    Ensure engine block deck is completely clean and dry. Position new cylinder head gaskets on engine block with all alignment dowels engaged. Verify gaskets are oriented correctly (UP markings facing up, FRONT markings toward front of engine). Ensure all coolant and oil passages align properly. Do not use gasket sealer unless specifically required by gasket manufacturer.
11. 11

    Install Cylinder Heads
    Carefully lower each cylinder head onto the engine block, aligning with dowel pins. Ensure head seats fully on gasket without shifting gasket position. Hand-start all 17 cylinder head bolts on each head to prevent cross-threading. Do not tighten bolts at this stage.
12. 12

    Torque Cylinder Head Bolts
    Torque cylinder head bolts in three stages following the proper sequence (start at center, work outward in a spiral pattern). First pass: torque all bolts to 25 ft-lbs. Second pass: torque all bolts to 50 ft-lbs. Final pass: torque all bolts to 65 ft-lbs. Follow the exact sequence for each pass. Allow engine to sit for 30 minutes, then verify final torque on all bolts.
13. 13

    Install Pushrods and Rocker Arms
    Apply assembly lube or engine oil to both ends of each pushrod. Install pushrods in their original positions, ensuring each seats properly in the lifter cup below. Install rocker arms, rocker arm balls, and rocker arm nuts on each stud. For hydraulic-lifter engines: tighten rocker arm nuts until all lash (free play) is removed, then tighten an additional 3/4 turn for proper hydraulic lifter preload. For solid-lifter (mechanical cam) engines such as the L76/L84, do NOT preload — set valve lash to the factory-specified clearance with a feeler gauge per the service manual.
14. 14

    Reinstall Exhaust Manifolds
    Position new exhaust manifold gaskets on cylinder heads. Install exhaust manifolds and start all 5 bolts per side finger-tight. Torque exhaust manifold bolts to 25 ft-lbs working from center outward. Reconnect exhaust pipes to exhaust manifold flanges with new gaskets and torque flange nuts to 35 ft-lbs.
15. 15

    Reinstall Intake Manifold
    Apply a thin bead of RTV silicone to the front and rear block-to-head joints (china walls). Position new intake manifold gaskets on cylinder heads, ensuring all port openings align. Carefully lower intake manifold into position. Install all 12 intake manifold bolts finger-tight. Torque intake manifold bolts to 30 ft-lbs in two passes, working from the center outward in a crisscross pattern.
16. 16

    Reinstall Distributor and Accessories
    Rotate engine to number one cylinder TDC on compression stroke. Install distributor with rotor pointing to number one cylinder position (as marked during removal). Install distributor hold-down and snug (but do not fully tighten for timing adjustment). Reinstall alternator brackets, power steering pump brackets, and all accessories removed during disassembly. Reconnect all vacuum lines, electrical connections, and hoses per photos/labels from disassembly.
17. 17

    Install Valve Covers and Complete Assembly
    Install new valve cover gaskets on valve covers. Position valve covers on cylinder heads and install all 6 bolts per side. Torque valve cover bolts to 45-60 inch-lbs (approximately 4-5 ft-lbs) in a crisscross pattern. Install spark plugs and torque to 15 ft-lbs. Reconnect throttle linkage, choke cable, and fuel line. Install air cleaner assembly. Reconnect heater hoses and temperature sender. Reconnect negative battery cable.

Reassembly

1. Refill cooling system with 10 quarts of DEX-COOL Extended Life Coolant (50/50 mix with distilled water)
2. Refill engine with 5 quarts of 5W-30 conventional engine oil and new oil filter
3. Before starting engine, prime oiling system by cranking engine with coil wire disconnected until oil pressure registers
4. Set initial timing to approximately 4-6 degrees BTDC, then fine-tune with timing light after engine reaches operating temperature
5. After first start, check for oil leaks, coolant leaks, and exhaust leaks while engine is warming up
6. Retorque cylinder head bolts after first heat cycle (engine reaches full operating temperature and cools completely). This is critical for gasket sealing.
7. Adjust valves (rocker arms) after initial break-in if any valvetrain noise is present

Verification

• Start engine and verify it runs smoothly without unusual noises, misfires, or rough idle
• Check for oil leaks around valve covers and any oil galley plugs on cylinder heads
• Check for coolant leaks around cylinder head gaskets, intake manifold, and water outlet
• Check for exhaust leaks at exhaust manifold gaskets and exhaust pipe connections
• Verify oil pressure reads within normal range (40-60 psi at operating temperature)
• Allow engine to reach full operating temperature and verify cooling system is functioning properly without overheating
• Perform final timing adjustment and idle mixture adjustment
• Road test vehicle and verify normal engine operation under load

More procedures for this vehicle