Cortina GT 500 Specification
The following is a specification for the Cortina GT 500 built in Australia. If my information is correct, between 90 and 120 cars were built, and some 30 are known to survive today.
Information is only given where it differs from standard G.T. car.
| Engine | Modifications | Comments |
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| Compression ratio 9.5:1 | Head polished, combustion chamber modified, inlet & exhaust ports cleaned up, also head shaved by 30 thou. | Power output 91 - 98 bhp. depending on state of tune |
| Lightened and balanced flywheel & clutch assembly. Heavier clutch pressure plate springs fitted | ||
| Special crankshaft pulley (smaller) | ||
| Special con-rod bolts with enlarged heads. (Believed to be from Transit V4 motor) | See parts list here | |
| Camshaft re-ground to revised specification. Power curve from 2,800 - 5,500 rpm. See Cams here | ||
| Spacer fitted to oil pump relief valve spring giving 10lbs/sq in increased pressure. | ||
| Carburettor | Modified chokes (27 and 29) and secondary main jet drilled to 135. | Many production needle and seats were the wrong size causing fuel starvation above 6,000 rpm. |
| Fuel Tank | Extra 8-3/4 gallon tank mounted in boot between suspension towers and against rear bulkhead. Twin filler caps on upper back panel (behind rear windscreen) | |
| Cooling System | No thermostat fitted. Cooling controlled by restrictor | Need info ?? ?? |
| Gearbox |
1st gear 2.50, 2nd gear 1.64, 3rd gear 1.23 4th gear 1 to 1 reverse 2.80:1 |
"Lotus" gearbox spec. First is very high resulting in possible increased clutch wear. |
| Exhaust system | Primary silencer cross baffles removed | |
| Final drive | 3.9 to 1 | |
| Suspension | Radius arms fitted at rear. | |
| Ride height lowered 2 inches all round. | ||
| Brakes | 9.5 inch X 0.375 inch front disks. Pad thickness 0.415 in. Special competition brake pads with alloy air scoops. Dust shields removed at front. | |
| Steering | 13.4 :1 ratio. Steering wheel 15.5 inches. Turning circle 33.75ft. | |
| Fuel Consumption | 24 mpg overall | 15 - 17 mpg during racing |
| Kerb Weight | 16.1 cwt (1803 lbs) | |
| Top Speed | 101 mph | G.T. top speed was 84 mph (Australia) |
Rear view of a GT500, showing twin filler caps behind rear window. Note that the original tank filler hole on the lower, rear panel has been blanked off. Almost every GT500 was 2-door, although there is some evidence for at least one or two 4-door cars. Notice the "500" badge next to the GT badge. Photo © Garry Saunderson.
Front view of a GT500. Note the twin air scoops under the front panel. They duct air onto the brake disks which do not have the normal dust shields fitted. The word "Cortina" in individual letters across the bonnet/hood must be peculiar to Australian Cortinas(?). Photo © Garry Saunderson
Inside the boot, showing the extra fuel tank and how the two tanks were connected. It allowed the cars to minimise pit stops. Two filler hoses and filler caps are fitted to the rear panel behind the rear windscreen. Photo © Garry Saunderson
Drawing showing the two fuel tanks in more detail. Total capacity was about 17 gallons. The strap across the boot-floor tank was an added feature to avoid "drumming" noises from the lower tank.
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Page last edited:- 10 July, 2005
