The greatest engine of all?

What appealed to Cole were wedge-shaped combustion chambers that required minimal machining after casting. Valves were fitted to the heads without separate guides and the four exhaust valves and four intake valves on each bank were in the same plane which also made machining simpler and faster.

In that era all GM divisions including Buick, Oldsmobile and Pontiac made their own motors and Cole was always keen to see what others were up to. At Pontiac he saw a clever design that engineer Clayton Leach had had to make in his home workshop because his bosses didn’t think it an idea worth developing. Instead of a long rocker shaft supporting individual rockers, Leach’s design featured a pressed steel rocker that engaged half a steel ball that was secured in place by a stud pressed into the head. The rocker was light, cheap to make, self-aligning and low in friction. If Pontiac didn’t want it, Chevrolet most certainly did.

Another talented GM engineer instrumental in the creation of the engine was John Dolza who had previously invented a means of simplifying how cylinder blocks were cast at the foundry. Green sand was poured into the mould box and then shaped in the bottom of the box. Cores, which defined cooling passages and bore cavities, were locked together and then positioned upside down in the mould over the green sand. This method reduced the number of cores needed from 22 in Cadillac’s V8 to only 12 in the new Chevy V8. The technique enabled the crankcase wall thickness to be reduced by half to just 0.156in yielding major weight and cost savings. Rather than the usual cast iron crankshaft, the SBC used forged steel piece for strength and lightness. Main bearings without the usual groove in the bottom half doubled the bearing’s load capacity by preventing oil seepage out its sides. It’s a feature that allowed the small block to develop tremendous horsepower as it was developed throughout its life.

Cole wanted the engine ready for production in double time and that’s what was delivered. John Dolza’s team of engineers, working long hours and weekends, completed the engine’s design in three months. Three weeks later a prototype was built. In a show of supreme confidence, production tooling was ordered before the first engine had even run. In early 1954 pilot production was started with the 265 cubic inch engine (4.3-litres) producing 162bhp with a two-barrel carburettor and a single exhaust, was duly fitted to the 1955 Bel Air sedan. Over 1.7 million would be sold that model year. But the new V8 would also find a home in a rather more sexy Chevrolet.

The Corvette had been launched as a concept car at GM’s Motorama show at the Waldorf-Astoria hotel in New York in January 1953. Interest in the new fibreglass bodied sports car was strong and full scale production started in July that year. Hardly surprising that the Corvette caught the eye of American enthusiasts as the car looked terrific. However, excitement paled somewhat when the stopwatches were brought out. Powered by the second generation of Chevrolet’s 235cu in (3.9- litre) Blue Flame in-line six, it produced a gross 150bhp, meaning the Corvette could only manage 0-60mph in about 11 seconds. Sure, this was the mid-fifties, but it was not a good look when even Oldsmobile’s Rocket 88 full-size sedan was quicker.

The new V8 was the answer. Weighing in at just 241kg, the small block was not only lighter than rival V8s at the time by around 45-68kgs, it was lighter even than the Blue Flame six by 27kg. Better still, fitted with a four-barrel carb and dual exhaust the motor made 195bhp in the 1955 Corvette, carving three full seconds off the crucial 0-60mph time.

One of those who had been taken by the Corvette show car in New York was a Russian-born Belgian engineer called Zora Arkus-Duntov. Post running his own company which among other things sold an overhead valve conversion for the Ford flathead V8, Arkus-Duntov had  worked at Allard in Clapham, London, but was busting to work at a company that had a sports car backed by a proper budget to develop it. After several approaches to GM management he was taken on by Ed Cole.

Not long after arriving at General Motors Arkus-Duntov produced a memo titled ‘Thoughts Pertaining to Youth, Hot Rodders and Chevrolet’. Cole was impressed, not least because he also wanted to radically change Chevrolet’s image and make its products appeal to a wider and younger audience. As a result three early small blocks were sent to Southern California’s Vic Edelbrock Jr, one of the prime movers of the West Coast hot rod movement. Edelbrock fitted a two-barrel intake manifold which increased power by 20bhp, fitted a set of Bob Hedman tubular exhaust manifolds and a hotter ignition system from the Spalding brothers. Another 20 and 10bhp respectively. Edelbrock Jr, described the small block as ‘God’s gift from heaven’.

He then started to develop fuel injection for the small block. The result was the Rochester Ram-Jet fuel injection system which as an option on the 1957 Corvette’s 283 cu in (4.6-litres) engine produced 250bhp. A further option was the Super Ram-Jet engine which came complete with a 10.5:1 compression ratio and a power output of 283bhp. It was the first American engine to produce 1bhp per cubic inch and it propelled the ’57 ‘Vette to a top speed of 132mph. Now it was a proper sports car.

With the Corvette on the right track, the small block also played its part on making a success of another soon be legendary Chevy. Launched in late 1966 for the ’67 model year, the Camaro was the GM’s answer to Ford’s incredibly popular Mustang. Naturally, racing the Camaro was the logical way to promote it and by combining the 101.6mm bore from the now standard 327cu in (5.4-litre) engine and a 76mm stroke crankshaft from the earlier 283cu in motor, a 302 cu in motor was created thus complying with the 5-litre capacity limit of the Sports Car Club of America Trans-Am championship which the Camaro duly won twice in succession.

That same 5-litre small block was used for Formula 5000 racing or Formula A as it was known in America, creating cars almost as quick as the F1 machines of that era. A few teams put Ford’s 302 motor in their chassis and fewer still tried Chrysler’s small block but the vast majority, used the Chevy. It also found its way into sports cars in other racing series, famously the Lola T70, which in MkIIIB form won the 1969 Daytona 24 Hours.

The descendants of the small block raced on, and have to date racked up no fewer than nine class wins at Le Mans since 2001.

The small block has made its mark in other arenas, too. Boating types might know that both Mercury’s and Volvo Penta’s inboard V8 engines are in fact marinesed versions of the small block. Bikers might be aware of the Boss Hoss, an American-made cruiser that uses one for motive power. Fitted longitudinally, the bikes are huge and not for the faint hearted when it comes to manoeuvring in tight spaces. Especially with an audience.

Ed Cole died in 1977, in a crash while at the controls of his twin-engine aircraft. He’d lived long enough to see the small block established as the powerplant of choice for ‘Youth and Hot Rodders’. Already a huge aftermarket industry catered for the engine, helped by the fact that the engine’s core design features never changed. Today mail order companies like Summit Racing can supply you virtually any part for a small block from aluminium blocks, aftermarket heads to exotic internal parts. Very affordable parts, too, with sexy forged pistons from as little as $350 a set. Speed costs money, but less of it if you go the small block Chevy route.

Hot rodders and drag racers on a time budget or who don’t have the know-how to build a hot small block from parts can log onto Chevrolet Performance Parts website and choose from a wide range of crate engines with many different power outputs. The only questions are  ‘What’s your budget and how fast do you wanna go?’

But what of the small block’s future? General Motors has declared that it will go ‘all electric’ by 2035. The company also announced in early February 2023 that it was developing a Generation VI small block and spending $854m on the task. No technical details have been given but I’d put a good bet on the new engine having 4.40-inch bore centres, two valves per cylinder and push rods. I mean, why change what’s worked so well for 70 years?