The potent 327 L84 held the title as the most powerful production small block Chevy engine for nearly 30 years! That’s an impressive feat for an engine developed way back in 1964, especially considering it gave up precious cubic inches to the larger small blocks developed later on.

So how did this legendary engine do it?

The original Chevy 327 was introduced in 1962 with Chevrolet’s new and larger 4.00-inch bore and 3.25-inch stroke size. At the time, the 327 was the largest displacement small block available, and the higher-compression, 4-barrel carb version of the engine easily achieved the one horsepower-per-cube level that the 283 small block had achieved a few years earlier. By 1964, Chevrolet was getting an amazing 365 horsepower from its carbureted 327 L76 small block.

But Chevy engineers still had another trick up their sleeve: mechanical fuel injection.

In 1964-65, Chevrolet offered an L84 version of the 327 topped with the latest iteration of the mechanical fuel injection system used on the 283. Unlike modern EFI (electronic fuel injection), Chevrolet’s Rochester fuel injection system metered out fuel mechanically using no electronics and just three main components: fuel meter, air meter, and intake manifold. Although rudimentary compared to today’s modern EFI system, the Rochester fuel injection system offered substantial top-end power over the similar carbureted setup on the L76.  The mechanical injection setup, along with 11:1 compression, “double hump” fuelie heads, aggressive solid lifter camshaft, and larger diameter valves, pushed the L84 to 375 horsepower—a whopping 1.146 horsepower-per-cubic-inch.

The 327 L84 remained the most powerful Chevrolet small block production engine ever until the quad-cam LT5 came out in the 1990s. And it was the most powerful naturally-aspirated single-cam small block until the arrival of the LS6 engine in the early 2000s.

It was an engine ahead of its time. That was also its downfall.

According to Super Chevy magazine, the carbureted L76 actually outsold the more powerful L84 because fuel injection was a foreign concept to many customers at the time. It was also significantly more expensive, causing many performance enthusiasts of the day to opt for carburetion. By mid-year 1965, Corvette owners could get their Stingray with a 425-horsepower, carbureted 396 big block that actually cost less than the 327 fuelie. Chevrolet discontinued the L84 following the 1965 model year.

But in just two years, the L84 left its mark as one of the top small blocks of all time.

Check out the #4 and #5 engines on our list here:

#5: The original 265
#4: 350 TPI L98



Author: David Fuller

David Fuller is OnAllCylinders' managing editor. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. He has also partnered with mainstream and trade publications on a wide range of editorial projects. In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing.