🏷️ Basic Information

Make:

Chevrolet

Model:

Corvette

Year:

1968

Engine Variant:

427 (L36, L68, L71, L88, ZL1)

Engine Displacement Code:

454

Vin Structure Era:

Pre-1981 (Model Year + Assembly Plant + Sequential Unit Number)

👋 Introduction

Segment:

High-performance sports car

Era Designation:

Second Generation Corvette (C2/C3 transition, though 1968 is the start of C3, sharing some aspects with late C2)

Competitors 1968:

Ford Mustang GT, Plymouth Barracuda, Dodge Charger, Porsche 911 (European), Jaguar E-Type (European).

Design Philosophy:

American performance icon, potent V8 engines, fiberglass body construction, driver-focused cockpit, iconic styling.

Performance Focus:

Emphasis on raw power, acceleration, and track capability, particularly with the 427 variants.

📋 Manual Details

Primary Focus:

Full Factory Service and Repair

Secondary Focus:

Maintenance, Troubleshooting, Diagnostics

Estimated Pages:

Hundreds (Exact count varies by edition and specific content, typically over 500 pages for a complete manual)

Type:

Factory Service Manual / Repair Manual

Language:

English

Format:

Download PDF

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, rebuilding, specifications, timing, lubrication, cooling system, fuel pump, ignition system (distributor, points, condenser, coil), carburetors (Holley/Rochester Quadrajet/Tri-Power), exhaust system.

Engine Performance Variants:

Detailed specifications and differences for L36 (390 hp), L68 (400 hp Tri-Power), L71 (435 hp Tri-Power), L88 (430 hp - often underestimated), and ZL1 (430 hp - aluminum block) 427 cubic inch Big-Block V8 engines.

Transmission:

Manual transmissions (4-speed Muncie M20, M21, M22) and automatic transmission (Powerglide 2-speed, Turbo Hydra-Matic 400) overhaul, repair, and specifications.

Drivetrain:

Clutch assembly, driveshaft, universal joints, rear axle assembly (Positraction/limited-slip differential options), half-shafts, wheel bearings.

Suspension:

Front suspension (upper/lower control arms, ball joints, kingpins, tie rods, steering knuckle), rear suspension (multi-leaf springs, trailing arms, U-joints), shock absorbers, sway bars.

Brakes:

Front disc brakes (calipers, rotors, pads), rear drum brakes (wheel cylinders, shoes, drums), brake fluid, master cylinder, power brake booster, parking brake system.

Steering:

Steering linkage, steering gearbox (recirculating ball), power steering system (pump, hoses, reservoir, steering column).

Electrical:

Battery, charging system (generator/alternator, regulator), starting system (starter motor), ignition system, lighting system (headlights, taillights, interior lights), gauges, wiring diagrams, fuse block, horn.

Body And Chassis:

Frame construction, body panels (fenders, hood, doors, roof, rear deck), weatherstripping, bumpers, glass, convertible top mechanism, interior trim, seats, dashboard, instrumentation.

Heating And Air Conditioning:

Heater core, blower motor, defroster system, optional air conditioning system components and service.

Routine Maintenance:

Oil changes, filter replacements, lubrication points, tune-ups, fluid checks and top-offs, belt adjustments.

Component Overhaul:

Complete step-by-step instructions for engine, transmission, differential, carburetor, and brake system rebuilds.

Troubleshooting:

Diagnostic charts, common problems and solutions, symptom-based troubleshooting guides.

Alignment:

Wheel alignment specifications and procedures (caster, camber, toe-in).

Wiring Diagrams:

Detailed electrical schematics for all vehicle systems.

Depth:

Comprehensive (from basic maintenance to full rebuilds and diagnostics)

Diagnostic Capabilities:

Advanced diagnostics for engine, electrical, and mechanical systems, including troubleshooting guides for specific issues.

📊 Manual Specifications

Format:

PDF

Resolution:

High-resolution scans suitable for printing clear text and diagrams.

Searchability:

Typically text-searchable PDF for quick information retrieval.

Binding:

N/A (Digital Download)

Paper Quality For Print:

N/A (Digital Download - User's printing choice)

⚙️ Engine Specifications

Engine Type:

Overhead Valve (OHV) V8, Big-Block

Displacement Cu In:

427

Bore In:

4.25

Stroke In:

3.875

Block Material:

Cast Iron (Standard), Aluminum (ZL1)

Cylinder Head Material:

Cast Iron (Standard), Aluminum (L88, ZL1)

Hp L36:

390 hp @ 5400 rpm

Torque L36 Lb Ft:

472 lb-ft @ 3600 rpm

Hp L68:

400 hp @ 5400 rpm (Tri-Power)

Torque L68 Lb Ft:

460 lb-ft @ 3600 rpm (Tri-Power)

Hp L71:

435 hp @ 5400 rpm (Tri-Power, higher compression)

Torque L71 Lb Ft:

460 lb-ft @ 4200 rpm (Tri-Power)

Hp L88:

430 hp @ 5400 rpm (Gross - often significantly higher in reality, aluminum heads, hi-lift cam)

Torque L88 Lb Ft:

470 lb-ft @ 4200 rpm (Gross)

Hp Zl1:

430 hp @ 5400 rpm (Gross - aluminum block and heads, often severely underrated)

Torque Zl1 Lb Ft:

470 lb-ft @ 4200 rpm (Gross)

Carburetor L36:

Single Holley 780 CFM 4-barrel

Carburetor L68:

Three Rochester 2-barrel carburetors (Tri-Power)

Carburetor L71:

Three Rochester 2-barrel carburetors (Tri-Power)

Carburetor L88:

Single Holley 850 CFM 4-barrel (high performance)

Carburetor Zl1:

Single Holley 850 CFM 4-barrel (aluminum manifold)

Fuel Pump:

Mechanical

Fuel Type:

Premium Unleaded Gasoline (91+ Octane Recommended for higher compression engines)

🔧 Transmission

Transmission Type:

4-speed Manual (Muncie M20, M21, M22 'Rock Crusher')

Transmission Type:

Automatic (Powerglide 2-speed, Turbo Hydra-Matic 400 3-speed)

Clutch:

Single dry plate (manual transmission)

Transmission Fluid Spec:

Refer to manual for specific fluid types (e.g., GL-4 for manual, Dexron for automatic)

📐 Dimensions

Length In:

175.0

Width In:

69.1

Height In:

47.9 (Coupe), 47.3 (Convertible)

Wheelbase In:

98.0

Front Track In:

55.1

Rear Track In:

55.4

Curb Weight Lbs:

Approx. 3,200 - 3,500 lbs (depending on engine and options)

Gross Vehicle Weight Rating Gvwr Lbs:

Refer to vehicle plate (typically around 4,000 lbs)

🛡️ Safety Features

Crash Test Data:

No standardized crash test ratings available for this era (NHTSA not established).

Braking System:

Four-wheel disc brakes (standard on 427 models), power-assisted.

Steering System:

Recirculating ball, optional power steering.

Seat Belts:

Standard lap belts (shoulder belts optional or part of specific packages).

Body Construction:

Reinforced steel frame, fiberglass body panels.

💡 Technology Features

Audio System:

AM/FM radio, optional AM/FM Multiplex stereo. Typically 2 speakers.

Instrumentation:

Full array of analog gauges: speedometer, tachometer, oil pressure, water temperature, ammeter, fuel gauge. Warning lights for brakes, oil, etc.

Cruise Control:

Optional on some models.

Smartphone Integration:

Not applicable for this era.

🔧 Maintenance

Oil Change Interval Miles:

Every 3,000 - 5,000 miles (or every 6 months), depending on usage. Manual may recommend more frequent changes for heavy use.

Tune Up Interval:

Annually or every 12,000 miles (includes spark plugs, points, condenser, distributor timing)

Transmission Fluid Change Auto:

Every 24,000 - 30,000 miles

Rear Axle Fluid Change:

Every 24,000 - 30,000 miles (or as recommended)

Engine Oil Type:

API Service Classification SG, SH, or SJ recommended (or equivalent for vintage engines); viscosity typically 10W-30 or 10W-40 depending on climate. High-zinc (ZDDP) content is beneficial for flat-tappet camshafts.

Engine Oil Capacity Quarts:

6 quarts (with filter)

Coolant Type:

Ethylene Glycol based antifreeze (e.g., Prestone or equivalent) mixed 50/50 with distilled water.

Brake Fluid Type:

DOT 3 (or DOT 4 if suitable)

Power Steering Fluid:

Automatic Transmission Fluid (ATF), Dexron II or equivalent.

Engine Cooling System:

Potential for overheating due to aging radiators, water pumps, and fan shrouds. L88/ZL1 engines, with their higher performance, require robust cooling.

Fiberglass Body:

Cracking or delamination of fiberglass body panels, especially around stress points. Repair requires specialized fiberglass knowledge.

Electrical System:

Aging wiring harnesses, corroded connections, and failing components (alternator, voltage regulator, ignition switch) can cause intermittent issues.

Carburetor Performance:

Wear in Rochester Quadrajet secondary barrels, leaks in Holley carburetors, and tuning complexities with Tri-Power systems.

Suspension Wear:

Worn ball joints, bushings, and tie rods can affect handling and alignment.

Engine Rebuild:

Rebuilds of the 427 Big-Block are common for performance restoration.

Brake System Overhaul:

Overhauling calipers, replacing brake lines, and replacing rotors/pads/shoes.

📚 Vehicle History

Founding Principles:

Chevrolet, founded by Louis Chevrolet, became known for affordable, reliable, and performance-oriented vehicles.

Motorsport Legacy:

Strong roots in racing, including IndyCar and NASCAR, influencing Corvette development.

C2 To C3 Transition:

1968 marked the introduction of the C3 generation (Mako Shark design), though initial models shared some traits with the outgoing C2 Sting Ray. The 427 Big-Block was a carryover performance option.

427 Significance:

The 427 Big-Block was Chevrolet's top-tier performance engine, offering immense power and becoming a legend in the Corvette lineage.

Production Years C3:

1968-1982

Production Volume 1968 Corvette:

28,566

Production Volume 1968 427 Models:

Approx. 6,000-7,000 (across all 427 variants, exact breakdown varies)

Manufacturing Location:

St. Louis, Missouri, USA

🏆 Awards & Recognition

Iconic Status:

Widely recognized as one of the most desirable and iconic American muscle cars and sports cars of the 1960s.

Collectibility:

Highly sought-after by collectors, with L88 and ZL1 models being among the most valuable and rare Corvettes ever produced.