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The Mustang 429 “twisted hemi”  on the ford seen in 1969.  Ford fans thought they had finally gotten a car to rival the high powered Corvettes, but, this was not what Ford intended for the high revving Mustangs.   The Boss 429 was developed to qualify 500 examples NASCAR. The 429 was the real deal with four-bolt mains, a forged steel crankshaft The big-port, staggered-valve aluminum heads with crescent-shaped combustion chambers gave it the nickname “Twisted Hemi” or “Semi Hemi”.  

It had a  735-cfm Holley four-barrel with ram-air, an aluminum high-riser, and header-type exhaust manifolds.  If you were lucky enough to get one you took the mandatory options including a four-speed and a 3.91:1 Traction-Lok rear. An oil cooler, trunk-mounted battery and  beefed up that featured  front and rear stabilizer bars, Polyglas F60X15s, quicker power steering, and power front discs.

The Boss 429s had a nicer interior and an 8000-rpm tach.  Don’t even think about air conditioning and automatic transmission because you couldn’t get them.  It had a beefed up front suspension to carry the twisted 429.  Handling was improved by a  wider front track and better geometry.

So here’s the specs:

Weight, lbs: 3,870
Number built: 858
Base price: $4,798
Fuel system: 1 x 4bbl.
Compression ratio: 10.5:1
Horsepower @ rpm: 375 @ 5200

Torque @ rpm: 450 @ 3400
0-60 mph, sec: 6.8
1/4 mile, sec. @ mph: 14.0 @ 103