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1968 GT500KR
Author: Dennis Begley's GT350 (more...)
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The 1968 Shelby Cobra gt 500
KR
King of the
Road
by Dennis Begley
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Ford offered the Cobra Jet engine for the
first time in 1968 1/2. Carroll Shelby, always one to up the
competition, be it Ford or GM, put the 428CJ engine in his GT500
Shelby Mustangs about two thirds into the model year. It was cheap
horsepower. Early '68 GT500's were given Ford's 428 police interceptor
engine. Rated at 360 hp at 5400 rpm, the big block produced 420 ft. Lbs.
Of torque at 3200 rpm. Mid-year, Shelby got wind that GM intended to
introduce a 396 Camaro and call it "King of the Road." Shelby
beat them to it. Before GM could follow through, Shelby American offered
a GT500KR, King of the Road, and stuffed the Cobra Jet engine
under the hood.
The '68 GT500KR was a very special car. Many modifications were
made to the stock GT Mustang. The 428 was the same Cobra Jet engine
offered in the stock big block Mustang. It was the old 428 block with
a lot of changes. The low riser, revised, 427 heads had huge rectangular ports. Measuring
2.34" x 1.34", the ports were larger than the 427 racing
heads. A special dual-plane intake manifold held the mammoth Holley
carb. Stronger connecting rods and crankshaft were replaced the
stock 428 pieces.
Dished alloy pistons were used with eyebrows, attached to con rods
with full floating pins locked in with two retainers. This lowered
the compression ratio to 10.7 to 1. Pop up pistons were available
for drag racers. The KRs all received heavy duty front and rear
shocks, the four speed cars got staggered rear shocks, power front
disc brakes and power steering and big capacity rear drum
brakes.
Ford did not promote the increase in horse power the Cobra Jet
engine had. It was advertised at 335 horse. That figure was off at
least 20 percent. Remember during those years the insurance
companies had started to penalize high horsepower cars. In fact,
these years were the beginning of the end of cars like the gt 500
KR. Total production of the KR's was 933 Fastbacks and 318
convertibles. One awesome machine....
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GT500KR Engine Specifications
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| Horsepower |
335 @
5,600 RPM |
| Torque |
440 @
3,400 RPM |
| Displacement |
428
CI |
| Bore |
4.12
Inches |
| Stroke |
3.98
Inches |
| Compression ratio |
10.7:1 |
| Cylinder Heads & Valves |
Large intake port with
2.06" intake valves,
1.625" exhaust valves |
| Intake Manifold |
Large
Iron version of aluminum manifold |
| Exhaust Manifold |
New
Version |
| Carburetor |
735 cfm
4V |
| Rocker Arms |
1.73:1 |
| Tappet - Cam |
Hydraulic
Lifters and Cam |
| Oil Pan |
Conventional
Ford 428 |
| Cam Shaft Lift |
.481
Intake
.490 Exhaust |
| Cam Shaft Duration |
290
Degrees |
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