🏷️ Basic Information

Make:

Chevrolet

Model:

Corvette

Year:

1968

Engine Code Prefix:

L36, L46, L68, L71, L89, ZL1

Generation Code:

C3

Generation Name:

Second Generation

Vin Engine Designator:

T (300 HP 327ci/5.4L V8, Turbo-Hydra-Matic), V (350 HP 327ci/5.4L V8, 4-speed Manual), P (300 HP 327ci/5.4L V8, 4-speed Manual - L30), S (365 HP 427ci/7.0L V8, 4-speed Manual - L36), R (400 HP 427ci/7.0L V8, 4-speed Manual - L68), N (435 HP 427ci/7.0L V8, 4-speed Manual - L71), M (460 HP 427ci/7.0L V8, 4-speed Manual - L89 Aluminum Heads), Z (430 HP 427ci/7.0L V8, 4-speed Manual - ZL1 Aluminum Block - Special Order)

👋 Introduction

Market Position 1968:

The 1968 Corvette represented Chevrolet's entry into the third generation (C3) of its iconic sports car, aiming to compete with European exotics and other American performance cars with its dramatic new styling and powerful V8 engine options.

Target Audience:

Enthusiasts, collectors, and owners of the 1968 Chevrolet Corvette seeking to perform maintenance, repairs, and restorations.

Key Competitors:

Ford Mustang, Mercury Cougar, Dodge Charger, Plymouth Barracuda, Porsche 911, Jaguar E-Type.

Design Era:

Revolutionary 'Mako Shark' inspired design, a significant departure from the C2 Sting Ray, featuring a long hood, short deck, and concealed headlights.

Performance Focus:

Offered a range of potent V8 engines, cementing its reputation as an American performance benchmark.

Manual Value Proposition:

Provides essential, accurate, and detailed information for owners and mechanics to maintain and restore the 1968 Corvette to factory specifications, crucial for preserving its classic status.

📋 Manual Details

Covered Models:

All Corvette C3 1968 models

Covered Engines:

327ci (5.4L) V8 L30, 327ci (5.4L) V8 L79, 427ci (7.0L) V8 L36, 427ci (7.0L) V8 L68, 427ci (7.0L) V8 L71, 427ci (7.0L) V8 L89, 427ci (7.0L) V8 ZL1

Covered Transmissions:

M20 (4-speed Manual), M21 (4-speed Manual Close-Ratio), M22 (4-speed Manual 'Rock Crusher'), TH400 (3-speed Automatic Turbo-Hydra-Matic)

Covered Trims:

Base Coupe, Convertible

Estimated Page Count:

Approximately 800-1000 (typical for comprehensive workshop manuals of this era, though exact PDF count may vary)

Manual Type:

Workshop Repair Service Manual

Language:

English

Format:

PDF Download

📖 Manual Coverage

Engine Mechanics:

Complete engine disassembly, inspection, assembly, tuning, lubrication system, cooling system, fuel system (carburetor and fuel pump), ignition system (distributor, coils, spark plugs), exhaust system, emissions control systems (if applicable for the era).

Transmission Drivetrain:

Manual transmission (Muncie M20/M21/M22) overhaul and repair, Automatic transmission (TH400) overhaul and repair, clutch system, driveshaft, rear axle assembly (Positraction and open differentials), universal joints, CV joints (if applicable).

Chassis Suspension:

Front suspension (independent, unequal length A-arms, coil springs, sway bar), rear suspension (independent trailing arms, transverse leaf spring), shock absorbers, steering system (power steering optional), wheel bearings, alignment specifications.

Brakes:

Front disc brakes (power assisted), rear drum brakes, brake fluid specifications, hydraulic system troubleshooting, parking brake system, brake component replacement and adjustment.

Electrical System:

Battery, charging system (alternator), starting system (starter motor), lighting system (headlights, taillights, turn signals), instrumentation (gauges, warning lights), wiper system, horn, power windows (optional), radio, wiring diagrams, fuse panel, troubleshooting electrical faults.

Body Interior:

Body panel removal and installation, doors, hood, trunk lid, bumpers, weatherstripping, interior trim, seats, dashboard, convertible top mechanism (if applicable), body repair techniques, rust prevention.

Maintenance:

Oil changes, filter replacements, spark plug replacement, tune-up procedures, fluid checks and top-offs, lubrication points, tire rotation, belt inspection and adjustment.

Troubleshooting:

Systematic diagnostic procedures for common and uncommon issues, symptom-based troubleshooting guides, electrical short/open circuit diagnosis, mechanical component failure analysis.

Repair Rebuild:

Detailed step-by-step instructions for component removal, disassembly, cleaning, inspection, repair, reassembly, and installation for all major systems.

Specifications:

Torque specifications for all fasteners, engine clearances (piston-to-wall, bearing clearances), valve lash settings, ignition timing, carburetor settings, alignment angles, fluid capacities.

Technical Depth:

Comprehensive, from basic maintenance and adjustments to full engine and transmission rebuilds, including advanced electrical diagnostics and bodywork repair.

📊 Manual Specifications

File Format:

PDF

Searchable Text:

Likely searchable text, enabling quick access to specific information.

Printability:

Printable pages for on-the-job use.

Resolution:

High-resolution scans of original factory documentation ensure clarity of diagrams and text.

Print Quality:

N/A (Digital PDF)

Binding Type:

N/A (Digital PDF)

Paper Type:

N/A (Digital PDF)

⚙️ Engine Specifications

Base Engine:

327 cubic inch (5.4L) V8

Base Engine Variant L30:

327ci (5.4L) V8, 2 V-belts, 300 HP @ 4800 RPM, 360 lb-ft @ 3200 RPM (with 2-barrel carburetor)

Optional Engine L79:

327ci (5.4L) V8, 4-barrel carburetor, 350 HP @ 5800 RPM, 350 lb-ft @ 3600 RPM (High-performance 327)

Big Block Engine L36:

427ci (7.0L) V8, 3x2-barrel carburetors (Tri-Power), 390 HP @ 5400 RPM, 470 lb-ft @ 3600 RPM

Big Block Engine L68:

427ci (7.0L) V8, 3x2-barrel carburetors (Tri-Power), 400 HP @ 5400 RPM, 460 lb-ft @ 3600 RPM (Higher compression ratio and cam)

Big Block Engine L71:

427ci (7.0L) V8, 3x2-barrel carburetors (Tri-Power), 435 HP @ 5800 RPM, 470 lb-ft @ 4000 RPM (High-lift camshaft, higher compression)

Big Block Engine L89:

427ci (7.0L) V8, 3x2-barrel carburetors (Tri-Power), 435 HP @ 5800 RPM, 470 lb-ft @ 4000 RPM (Same as L71 but with aluminum cylinder heads)

Big Block Engine Zl1:

427ci (7.0L) V8, 3x2-barrel carburetors (Tri-Power), 430 HP @ 5200 RPM (rated), 470 lb-ft @ 4000 RPM (rated) (Full aluminum block, forged internals - race-bred, special order)

Compression Ratio L30:

8.8:1

Compression Ratio L79:

10.25:1

Compression Ratio 427S:

10.25:1 (L36, L68, L71, L89), 12.0:1 (ZL1 - advertised rating)

Fuel System Type:

Carbureted (Rochester Quadrajet 4-barrel for most 327 and 427, Rochester 2-barrel for base 327, Triple Rochester 2-barrels for Tri-Power 427s, specific Holley carbs for L71/L89/ZL1)

Fuel Pump Type:

Mechanical fuel pump

Fuel Requirement:

Premium Unleaded Gasoline (91+ octane recommended)

🔧 Transmission

Standard Transmission:

Muncie M20 4-speed Manual (on most models)

Optional Transmission Manual:

Muncie M21 4-speed Manual (Close-Ratio), Muncie M22 4-speed Manual ('Rock Crusher' - Heavy Duty)

Optional Transmission Automatic:

Turbo-Hydra-Matic TH400 3-speed Automatic

Clutch Type:

Single dry plate, hydraulically actuated (manual transmission)

Rear Axle Ratio:

Varied by engine and transmission, typically ranging from 3.08:1 to 4.11:1, including Positraction limited-slip differential options.

📐 Dimensions

Wheelbase:

98.0 inches (2489 mm)

Overall Length:

175.1 inches (4448 mm)

Overall Width:

69.1 inches (1755 mm)

Overall Height Coupe:

47.8 inches (1214 mm)

Overall Height Convertible:

47.2 inches (1199 mm)

Front Track:

56.1 inches (1425 mm)

Rear Track:

58.3 inches (1481 mm)

Curb Weight Est:

3,100 - 3,400 lbs (approx. depending on engine and options)

Gross Vehicle Weight Rating Est:

Approximately 3,700 lbs

Trunk Volume Est:

Approximately 10.7 cubic feet

🛡️ Safety Features

Safety Ratings Era:

Safety standards were significantly different in 1968; formal crash test ratings as we know them today were not widely available or standardized.

Active Safety Features Standard:

Four-wheel hydraulic disc brakes, independent suspension for superior handling.

Active Safety Features Optional:

Power steering (improves maneuverability), Positraction differential (enhances traction).

Passive Safety Features Standard:

Three-point seat belts (introduced as standard on most new cars in 1968), padded dashboard and steering wheel, shatter-resistant windshield.

Passive Safety Features Optional:

Headrests (optional on some models).

💡 Technology Features

Infotainment Options:

AM/FM radio, AM/FM Multiplex radio (Stereo), optional 8-track tape player.

Speakers:

Typically two speakers (dash-mounted), with optional rear speakers for some models.

Driver Assistance Features:

None by modern standards. Focus was on driver control and mechanical feedback.

🔧 Maintenance

Oil Change Interval:

Every 3,000 miles or 6 months, whichever comes first. (Based on typical recommendations for the era; modern synthetic oils may allow for extended intervals but consult with a specialist for classic car use).

Oil Filter Replacement:

Replace with every oil change.

Tune Up Recommendation:

Inspect and replace spark plugs, points, condenser, distributor cap and rotor at approximately 12,000-15,000 miles or annually. Check ignition timing annually.

Transmission Fluid Change:

Manual: Inspect fluid level every 12,000 miles. Automatic: Change fluid and filter every 24,000 miles (or as per service manual for heavy-duty use).

Coolant Flush Interval:

Flush and replace coolant every 24,000 miles or 2 years.

Engine Oil Type:

API Service Classification SE or SD (check original manual for specific viscosity recommendations, typically 10W-30 or 10W-40 for general use). For classic cars, consider high-zinc (ZDDP) content oils for flat-tappet camshaft protection.

Engine Oil Capacity:

5 US quarts (4.7 L) with filter for 327ci; 6 US quarts (5.7 L) with filter for 427ci.

Transmission Fluid Manual:

GM Synchromesh Transmission Lubricant (or equivalent GL-4 rated gear oil). Capacity: Approximately 2.0 US quarts (1.9 L).

Transmission Fluid Automatic Th400:

Dexron III/Mercon ATF. Capacity: Approximately 1.5 US quarts (1.4 L) for refill, 3.5 US quarts (3.3 L) for change with filter.

Brake Fluid Type:

DOT 3 or DOT 4 Heavy Duty Brake Fluid (glycol-based).

Coolant Type:

Ethylene Glycol based antifreeze mixed 50/50 with distilled water.

Common Issues Electrical:

Aging wiring harnesses can lead to intermittent electrical faults, corrosion in connectors, failing relays, and issues with the headlight vacuum system.

Common Issues Mechanical:

Carburetor adjustment and tuning, vacuum leaks, aging weatherstripping leading to water intrusion, suspension wear (bushings, ball joints), potential for overheating in heavy traffic with larger engines without proper cooling system maintenance.

Common Issues Body:

Corrosion, particularly around wheel wells, rocker panels, and chassis components. Fiberglass body cracks or delamination can occur with age or impact.

📚 Vehicle History

Chevrolet Heritage:

Chevrolet, founded in 1911, has a long history of producing a wide range of vehicles, from economy cars to trucks and performance automobiles. The Corvette, introduced in 1953, is its flagship sports car, embodying American automotive performance and style.

C3 Introduction:

The 1968 model year marked the debut of the C3 generation, a completely redesigned Corvette with styling heavily influenced by the Mako Shark II concept car. It was a bold statement for Chevrolet, moving away from the previous generation's lines.

1968 Specifics:

Notable changes for 1968 included the introduction of the T-tops on the coupe body style, concealed headlights, and a wider range of engine options, including the formidable 427 cubic inch Big Blocks.

Production Location:

St. Louis, Missouri, USA

Production Volume 1968:

28,566 units produced for the 1968 model year.

Key Personnel Design:

Larry Shinoda (exterior design lead), Zora Arkus-Duntov (chief engineer, instrumental in performance development).

🏆 Awards & Recognition

Automotive Icon Status:

The C3 Corvette, particularly the 1968 model year, is recognized as a significant milestone in automotive design and performance, holding a strong place in automotive history and collector circles.

Collector Value:

Highly sought after by collectors, with values varying significantly based on engine, options, condition, and originality. The L89 and ZL1 models are particularly rare and valuable.

Historic Vehicle Status:

Many 1968 Corvettes are eligible for historic vehicle registration and related benefits in various regions, recognizing their classic status.