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The name AC is indelibly linked with the likes of Carroll Shelby and the Shelby Cobra. Carroll Shelby certainly brought AC from obscurity into the fullness of the spotlight, but what some may not know is that AC was a well-established automaker for 59 years previous to the chicken farmer’s fateful V8 swap. It’s time we took a closer look at the AC Ace “Ruddspeed” that would one day inspire one of the greatest racing cars ever made. 

the 1963 AC Ace Ruddspeed was the car that inspired Carroll Shelby to build the Shelby Cobra
1963 AC Ace Ruddspeed | Sotheby’s

Was the Shelby Cobra the first Custom AC Ace? 

AC has converted to making EVs these days, but there is a long gas-burning history that led up to this. So, not only was AC making cars in the U.K. for a long time before Shelby came around but there was also already a racer/car dealer who had made a hot version of the super-light roadster. 

According to Autoblog, English car dealer and racing driver Ken Rudd also ran a performance shop where he customized the AC Ace. In fact, his speed shop, Ruddspeed, had built its reputation on customizing these little roofless racers. Rudd only built 37 of them and one example from 1963 is headed to the RM Sotheby’s auction block during Monterey Car Week. 

What engine did the original AC Ace have in it? 

In 1953, when the AC Ace came out, just like every other British roadster at the time – Austin Healey, MG, Triumphs, and so on –  AC used a very underwhelming 102-hp straight-six. Rudd’s claim to fame was sourcing a Bristol 2.0-liter straight-six making 120 hp and dropping that into the Ace. This proved to be a very popular mod. In 1961, the Bristol engine sourcing dried up and Rudd swapped to the Ford Zephyr’s 2.6-liter. Rudd ended up getting 170 hp out of these tuned Ford motors. 

It was these AC cars that grabbed hold of Carroll Shelby’s attention. With that seed planted, Shelby began cooking up the idea for the Shelby Cobra. Once Shelby ordered an Ace to California in February of 1962, the Ruddspeed cars’ days were numbered. 

What would soon follow was a torrent of interest around these little British roadsters. That interest quickly turned into full-blown glory and adoration from not only Americans but the whole of the motoring world. 

Carroll Shelby may have stood on the shoulders of Ken Rudd and the AC Ace “Ruddspeed”, but he managed to elevate the cute little roadster into something that would come to dominate the world’s most powerful racing teams. The AC Shelby Cobra was the definition of a world-beater and remains that to this day. 

What is an AC Ace Ruddspeed worth today? 

Carroll Shelby, the father of the Shelby Cobra, wearing his overalls while pushing a motorcycle.
Carroll Shelby | ISC Images & Archives via Getty Images

Seeing as how Rudd made very few and how they impacted Carroll Shelby, one can assume they will fetch a pretty penny. As we mentioned earlier, one example from 1963 is headed to the RM Sotheby’s auction block during Monterey Car Week. This particular one is the Rudspeed Ace Stage 4 tune, also with 170 hp due to tunes like new aluminum cylinder heads and triple SU carbs. For perspective, that’s 101 horsepower less than is found in the 289 Cobra, but the Ruddspeed weighed 400 pounds less than the small-block Shelby. RM Sotheby’s has set the pre-sale estimate at $300,000 to $375,000. 


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