Ford was introduced 385 big block V8 engine series In the late 1960s MEL (Mercury Edsel Lincoln) phased out the big-block design. The 385 big block, named after the 3.85-inch crankshaft stroke used in the initial 460 cubic-inch displacement offering, will eventually replace the Ford FE big block as well. During The 460-cubic-inch 385-series V8 powered Ford’s largest automobile modelsThe 429 cubic-inch derivative quickly won over the Ford performance crowd.

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Ford Boss 429 and 429 Super Cobra Jet engines They were at the peak of big-block Ford Mountain performance in the late 1960s and early 1970s. While these engines were fitted to a select few cars, the less ambitious 429 big-block was drafted under the Cobra Jet and Thunderjet banners.

The Thunderjet was the least powerful of the 429 cubic-inch groups, with a 360 horsepower rating. According to figures announced by Ford at the time, the switch to the 429 Cobra Jet yielded an additional 10 horsepower. While reported power ratings are often considered suspiciously low, the Cobra Jet’s advanced parts list is undeniable.

(Featured image by Sicnag via Wikimedia Commons | Cropped and scaled | CC BY-SA 2.0)

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While factory-reported power ratings are well below the actual output provided by any of the 429 big-blocks reviewed here, we’ll stick with those for our comparison. As mentioned, Ford reports 360 horsepower from the 429 Thunderjet with torque ratings of 480 lb-ft. The decidedly higher-performance 429 Cobra Jet, on the other hand, was rated at 370 horsepower but somehow lost 30 lb-ft of torque at 450 lb-ft.

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The 429 Thunderjet and Cobra Jet had similar two-bolt main bearing 385 big block architecture, but the 429 Cobra Jet block had stronger webs around the main bearings. The major differences between the two were the compression ratio, cylinder head construction, and carburetors.

A 600 CFM (Cubic Per Minute) four-barrel Autolite carburetor fed fuel to the 429 Thunderjet through 2.09-inch intake valves. The fuel-air mixture was compressed to a 10.5:1 ratio before ignition, and spent gas was expelled from the cylinder through 1.65-inch exhaust valves. Ford 429 Cobra Jet engines were fed by 700 CFM Rochester carburetors. Larger intake and exhaust valves, 2.24 and 1.72 inches respectively, were placed in free-flowing cylinder heads with smaller combustion chambers. Smaller baffle heads increased the compression ratio to 11.3:1.

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