1968 Mercury Cyclone GT 428 Cobra Jet

Muscle car powered by Ford 428 Cobra Jet V8.

Maroon 1968 Mercury Cyclone GT fastback with a visible 390 badge; exact-year GT body context, not a depiction or proof of the 428 option

Body Cyclone GT formal-roof or fastback hardtop

Engine 428 Cobra Jet four-barrel V8, 335 hp reported

Reviewed transmission Automatic documented on period test cars; full choice matrix unresolved

Production GTs included in all-engine Cyclone body totals; exact 428 subtotal unresolved

Story

1968 Mercury Cyclone GT 428 Cobra Jet

The 428 Cobra Jet arrived as a mid-model-year engine option in the 1968 Cyclone GT. It did not create the later 1969 Cyclone Cobra Jet or Spoiler model identity. Mercury offered the 1968 Cyclone GT in formal-roof hardtop and fastback hardtop bodies, and the engine option must be established separately from the GT body and appearance package.

Ford's high-performance catalog rates the regular-production 428 Cobra Jet at 335 horsepower and 440 lb-ft, with 11.0:1 compression and a 735-cfm four-barrel carburetor. Reviewed period road tests document an automatic-transmission Cyclone GT. The complete manual/automatic availability matrix and target-specific axle requirements remain unresolved; the tested Motor Trend car used 4.11 gearing, which is preserved as test-car evidence rather than a universal specification.

Mercury's production summary lists 1,368 formal-roof Cyclones and 12,260 fastback Cyclones, with Cyclone GT production included in those regular Cyclone totals. It does not provide a GT or 428 Cobra Jet subtotal. No exact target production quantity is asserted here.

Factory literature documents GT bucket seats, Comfort-Weave vinyl, deluxe steering wheel, heavy-duty springs and shocks, a large front stabilizer, GT identification, tape stripes, and GT wheel covers. Authentication must reconcile the body and GT equipment with factory paperwork, engine castings and dates, carburetor and induction, transmission, axle tag, paint, and trim. The licensed gallery car is an exact-year Cyclone GT with a visible 390 badge and is used only to show the shared GT body and trim; it is not presented as a 428 Cobra Jet.

**1968 Mercury Cyclone GT front view; exact-year GT context, not 428 evidence**Chad Horwedel via Flickr · CC BY-NC-ND 2.0

Price history

Values

Nominal dollars from original price sheets, auction archives, and approved value references.

Original Price

Base MSRP $3,703

1968 Mercury Cyclone GT Base MSRP (f.o.b. Detroit) (1968)
Manufacturer's suggested retail price (MSRP) f.o.b. Detroit reported in the specifications block of the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $7

4.11:1 Axle Ratio Option (1968)
Factory-installed 4.11:1 axle ratio option price reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $288

428 Cobra Jet V8 Engine Option (1968)
Factory-installed Cobra Jet engine option price reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $168

Cyclone GT Equipment Group Package Option (1968)
GT Package option price (including upper/lower body stripes, GT insignia, heavy-duty springs and shocks, front stabilizer bar, and twin bucket seats) reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $45

Goodyear Polyglas Tires Option (1968)
Goodyear Polyglas tires option price reported as $45.40 in the specifications block of the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $65

Power Front Disc Brakes Option (1968)
Factory-installed power front disc brakes option price reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $95

Power Steering Option (1968)
Factory-installed power steering option price reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $226

Select-Shift Cruise-O-Matic Automatic Transmission Option (1968)
Factory-installed automatic transmission option price reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference
Option price $64

Traction-Lok Differential Option (1968)
Factory-installed Traction-Lok differential option price reported in the August 1968 Motor Trend road test.
1968 Mercury Cyclone Cobra Jet road test (August 1968) - Pricing Reference

Values move with paperwork, originality, options, condition, venue, and body style. High bids and guide values are labeled separately from completed sales.

Reference records

Options, Colors & Components

Source-backed details for trim, chassis, production, and authenticity.

Engine Details

Bore 4.13 in · Regular-production Ford 428 Cobra Jet V8 specification · engine assembly / specification
Stroke 3.98 in · Regular-production Ford 428 Cobra Jet V8 specification · engine assembly / specification
Compression ratio 11.0:1 · Regular-production Ford 428 Cobra Jet V8 specification · engine assembly / specification
Rated horsepower 335 hp at 5,200 rpm · Regular-production Ford 428 Cobra Jet V8 specification · engine assembly / specification
Rated torque 440 lb-ft at 3,400 rpm · Regular-production Ford 428 Cobra Jet V8 specification · engine assembly / specification
Carburetor flow rating 735 cfm · Regular-production Ford 428 Cobra Jet V8 four-barrel carburetor specification · carburetor / specification
Spark plug BF-32 · Regular-production Ford 428 Cobra Jet V8 specification · ignition / specification
Firing order 1-5-4-2-6-3-7-8 · Regular-production Ford 428 Cobra Jet V8 specification · ignition / specification
Intake valve diameter 2.08 in · Regular-production Ford 428 Cobra Jet V8 specification · valve train / specification
Exhaust valve diameter 1.65 in · Regular-production Ford 428 Cobra Jet V8 specification · valve train / specification

Transmission

Factory transmission Three-speed automatic documented on period road-test cars
Factory transmission Four-speed manual
Factory transmission Select-Shift Cruise-O-Matic automatic

Options

428 Cobra Jet reference for the 1968 Mercury Cyclone GT 428 Cobra JetClassic Muscle · Reference illustration

Cyclone GT equipment group factory · performance · Sales literature lists bucket seats, deluxe steering wheel, heavy-duty springs/shocks/front stabilizer, GT wheel covers, GT identification, wide rims/tires, exhaust details, and tape stripes as Cyclone GT standard equipment. Exact order code not captured.
Cobra Jet engine option/package factory · performance · Period road tests document factory-installed Cobra Jet engine in Cyclone/Cyclone GT test cars; exact Mercury order code and mandatory companion equipment unresolved.

Paint

B Black Cherry factory · solid
D Nordic Blue Poly factory · metallic
F Madras Blue Poly factory · metallic
I Lime Frost Poly factory · metallic
M Polar White factory · solid
N Diamond Blue factory · solid
O Sea Foam Green factory · solid
P Pewter Beige Poly factory · metallic
Q Glacier Blue Poly factory · metallic
R Augusta Green Poly factory · metallic
T Cardinal Red factory · solid
U Caribbean Blue Poly factory · metallic
W Saxony factory · solid
X Wellington Blue Poly factory · metallic
Y Grecian Gold Poly factory · metallic
2 Tahitian Rose Poly factory · metallic
3 Calypso Coral factory · solid
6 Fawn factory · solid

Appearance

Upper and lower body tape stripes / GT stripes factory · stripe
GT identification factory · badge
GT turbine-styled wheel covers with wide-rim wheels factory · wheel

Interior

Twin bucket seats factory · seat
Comfort-Weave vinyl bucket-seat upholstery factory · upholstery
Deluxe steering wheel factory · steering wheel
Sports console optional · console

Chassis

Heavy-duty springs, shocks, and front stabilizer associated with GT package Suspension · factory
Independent SLA front suspension with ball joints and coil springs; rear leaf-spring drive/torque path Suspension · standard
Heavy-duty front coil springs (265 lb/in rate) Suspension · factory
Heavy-duty 0.85-inch front stabilizer bar Suspension · factory
Heavy-duty 4-leaf parallel semi-elliptic rear leaf springs (133 lb/in rate) Suspension · factory
Heavy-duty 1.18-inch piston shock absorbers Suspension · factory
Power front disc brakes Brakes · optional
Semi-floating rear axle Rear axle · standard

Production

Transmission Records reference for the 1968 Mercury Cyclone GT 428 Cobra JetClassic Muscle · Reference illustration

1968 Cyclone formal-roof hardtop by body · 1,368 · reported
1968 Cyclone fastback hardtop by body · 12,260 · reported

Authenticity

Rear Axle Records reference for the 1968 Mercury Cyclone GT 428 Cobra JetClassic Muscle · Reference illustration

Cyclone GT body and equipment Body style, bucket-seat GT interior, GT identification, stripes, wheels, and chassis equipment should agree with factory records · VIN and door tag, invoice, build sheet, Marti report, and installed equipment · trim correctness
428 Cobra Jet engine identity Factory paperwork and engine components must establish the mid-year 428 Cobra Jet option · Invoice, build sheet, Marti report, block and head castings/dates, carburetor, intake, and exhaust · fraud detection
Transmission and axle agreement Transmission type, tag, axle ratio, differential, and dates should agree with the individual build records · Transmission tag, axle tag, invoice, build sheet, or Marti report · numbers matching
Paint and trim agreement Paint, stripe, interior, wheel, and option codes should agree with the door tag and records · Door tag, hidden original finish, invoice, build sheet, or Marti report · trim correctness
1968 warranty-number 428 engine-code distinction The reviewed 1968 Ford/Mercury warranty-number table separates 428-cu-in 4V engine codes, including Q for 428 4V, P for 428 4V Police, and W for 428 4V Hi-Perf; the source does not by itself map those codes to a specific Cyclone GT Cobra Jet build. · Fifth character of the warranty number/VIN and corroborating invoice, build sheet, Marti/Ford record, or original door tag. · fraud detection

Still Researching

engine Normalized 428 Cobra Jet bore, stroke, compression, rated horsepower, rated torque, carburetor flow rating, spark plug, firing order, and valve-size specifications are now recorded from the Ford high-performance parts catalog; complete casting numbers, carburetor list numbers, distributor identifiers, exhaust identifiers, and date-code matrices remain unresolved.
transmission A period Cobra Jet Mustang/Cyclone/Cougar page reports four-speed manual and Select-Shift Cruise-O-Matic automatic availability for Cobra Jet Cyclone, and prior road tests document automatic test cars; exact Mercury order codes, gear ratios, shifter details, date windows, and transmission tags remain unresolved.
rear axle A 4.11 road-test-car ratio and model-line axle construction are recorded, but the complete factory ratio and limited-slip application chart is not.
brakes Front discs are documented as optional and on test cars, but mandatory status with the 428 option is unresolved.
suspension GT heavy-duty suspension specifications are now fully documented, including a 265 lb/in front spring rate, a 133 lb/in rear spring rate with 4 leaves, a 0.85-inch front stabilizer bar, and 1.18-inch heavy-duty shocks. Specific Ford/Mercury catalog engineering part numbers for these suspension components remain unresolved.
option packages GT and Cobra Jet equipment are recorded, but exact order codes, mandatory companions, and prices are incomplete.
production Cyclone body totals include GTs and all engines; no 428 Cobra Jet GT subtotal is established.
paint colors Eighteen model-year Mercury colors are recorded, but target frequencies and individual combinations are not.
trim and appearance Major GT cues are recorded, but every stripe, wheel, tire, exhaust, badge, hood, and molding combination is not.
interior GT bucket-seat and Comfort-Weave context is recorded, but the full trim-code and option matrix is incomplete.
authenticity markers A 1968 Ford/Mercury warranty-number table now documents distinct 428 4V engine-code rows, partially resolving the VIN-code distinction facet; exact Cyclone GT Cobra Jet code mapping, car-specific paperwork, and complete casting/date guidance remain unresolved.