[olddog]

Some years back a person who purchased and still owned an original sent me some PDFs of scanned original Shelby specs. I will past from the PDFs.

This is the 427 Competition Cobra:
Water cooled V-8, with cast iron block, magnesium
intake manifold, alloy cylinder heads,
lightweighvt alvesa nd alloyw ater pump.
Bore & stroke . .4.24 x 3.7B in
Displacement 427 cu in
C o m p r e s s i o n r a t i o . . . 1 2 . 4 : 1
Horsepower. . . . . . . 4 8 0 @ 6500 rpm
Torque 510 ft-lbs @ 3700 rpm
Carburetion .4 V Holley

This is the 427 Street Cobra:
Water-cooleVd -8,w ith cast iron block,5 main
bea ri ngs
Bore & stroke . .4.24 x 3.78 in, 107 x 96 mm
Displacement . . . . .427 cu in, 6998 cc
Compressiorna t i o . . . . . . . 1 0 . 4 t o o n e
Carburetion . .Two 4-bbl Holley
Valveg ear Pushrod-OHV
Horsepower (SAE) . . .425 bhp @ 6000 rpm
Torque . . 480ft-lbs@ 3700 rpm

This is the 428 StreetCobra:
428 CID Speclal Police Interceptor Ing'inc r'riih rnod'fii caticns
by Shel by Ameri can.
l^lat,er cooled, crst il"oir block witit 5 ma'in bear-ings
Sore 4.13 Siroke 3.9t] Dispjacetnent q28 cubic irrches-70l4cc
Compression ratio 10.0:l Carburet'ion 1-4V Ford
Horsepower 390 @ 5000 RPM Torque 475 f t 1bs. @ 3700 RPM

The cammer never went into any production cars nor Cobras. Shelby was known to be less than totally honest, so read this with a grain of salt. Also remember that in the 1960's Hp was flywheel on a dyno with no belts attached and air cleaners and exhaust did not need to resemble what would be in the car. In the early 1970's, the government said they had to be dynoed as installed in the car (all belts, air cleaner, and exhaust). If you look at the specs you will see all manufactures seemed to loose about 100 Hp that year. Keep that in mind when you compare to today's numbers.