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Medcalf Fiat 500


This is the Story of the Mighty Mouse, by owner Ian Medcalf.

Built by Peter Day in 1978 for circuit racing in the 850cc Special Saloon Class.

Peter built the car specifically around its unique Gordon Allen 850cc 2 cylinder ½ BDA engine. The engine required very short exhausts to produce its impressive 115 BHP and 112 lb/ft torque and the rear-engined Fiat 500 provided the ideal home!

Peter had considerable success with the car before moving on to compete in the MG Metro Challenge. 

The 500 was sold and went to Scotland to be raced and the BDA was replaced with a rather more conventional BMC ‘A’ Series engine.


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I found the car in Chorley, Lancs. in 1987 looking rather sorry for itself in a back yard, under a sheet, covered in snow  and paid £500 for the ‘engineless’ remains!

Then began the extended rebuild/restoration which took me 16 years!  It returned to competition in Hill Climbing and Sprinting in September 2003.

The car competes in the Sports Libre class up to 2 litres against cars such as Radicals where wins for this little 1380 cc car are hard to come by! 


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Despite the odds, notable successes include a class win at the Barbon Hill Climb and Fastest Time of the Day at Scammonden Hill Climb.  The Mighty Mouse has also taken the Best Prepared car awards at Barbon, Three Sisters and Curborough.

Ian Medcalf – Owner/Driver



Chassis    Tubular Space Frame

Body    Fibre Glass


Independent front and rear, Twin unequal length wishbones, Leda coil over shock absorbers


Front: 265mm diameter solid discs and four piston callipers

Rear: 220mm diameter solid discs and two piston callipers


3 piece split rim Compomotive  - Front 6 x 13; Rear 8 x 13


Avon A15 Front 6.2/20-13  Rear 8.2/20-13


Swiftune 1380cc A Series

DC5/2 crankshaft, pistons and connecting rods

Dry decked

Simplex timing chain

SW23 cam shaft

5 port cylinder head to Rally/Sprint spec  - 36mm inlet and 30mm exhaust valves

Forged 1.5:1 ratio rockers

Feather light fly wheel and back plate

Grey diaphragm and sintered race clutch plate


Swiftshift straight cut dog box

Straight cut 1:1.087 drop gears

4.7:1 straight cut crown wheel and pinion

Tran X limited slip differential


Webber 45 DCOE


141 BHP @ 7,500 rpm

108 lb/ft @ 6,000 rpm

Top speed 93 mph

0-60 – Don’t know but under 4 seconds!!


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