Corvette L76 327 Engine History, Specs, and Build Ideas
While the LS platform has pretty much taken over the world of hot rodding, it is really just a continuation of the nearly 70 years of absolute domination by the small block Chevy (SBC), which began in 1955 with the 265 cubic-inch V8 that was developed to replace the straight six in the Corvette and Bel-Air models. The Corvette has been the primary development catalyst for all GM gas V8 engines, if it is new and more powerful, you can rest assured it was bolted into a Corvette first. In 1964, GM released the L76 327ci V8 for the Corvette Sting Ray and with 365 horsepower and 350 lb-ft of torque, the L76 made the world’s most popular fiberglass car fly.
History of the Chevrolet 327- It’s Got a Corvette Engine!
The L76 is one of, if not THE engine responsible for the moniker “Corvette engine” that, to this day, gets thrown around in for-sale ads, car shows, cruise nights, and just general gearhead discussions. The only vehicles that received an L76 327 from the factory are Corvettes, so it is quite literally a “Corvette engine”. What makes this engine so special? Is it the fact that it is a single model engine, the specs, or something more ethereal? In reality it is probably a little bit of all of it. GM really likes to use similar codes, the 327 SBC was made with 6 RPO codes- L30, L74, L75, L76, L79, and L84. While GM used the 327 at some point in most models in the 1960s, the L76 and L84 are Corvette only.
What is an L76 327 Engine?
The 1964 L76 is an iron block 327 cubic-inch small-block engine served up with a 4-barrel carb (or mechanical fuel injection for the L84 variant.) The L76 and L84 Fuelie were the most powerful GM small block engines ever built, a title they held until 2001 when the LS6 came out, in a Corvette no less. The L76 engine horsepower peaked at 365 with 350 lb-ft of torque, while the L84 hit 375hp with the same torque. The high L76 compression ratio of 11:1 is a big part of the power potential of the L76 and L84 engines. The L76 1963 Corvette 327 engine was rated at 340 horsepower. The engine was updated in 1964, upping the power to 365 hp for the top-dog 1964 Corvette 327 Engine. A 1963 L76 is not the same as the 64-up L76.
These engines are not maxed out, but they are limited to about 5600 rpm in stock form. If you are building a max-performance 327, they can be spun to about 8000 rpm, but that requires solid lifters (which the L76 has), but you wouldn’t do that with an original 1964 327, these are fairly rare engines, only 5,011 were built.
L76 Chevy 327 Engine Specs:
Horsepower: 365hp @ 6,200 rpm
Torque: 350 lb-ft @ 4,000 rpm
Compression Ratio: 11:1
Displacement: 327 cubic inches
Cylinder Bore: 4.001”
Stroke: 3.25”
Heads: Iron “double-hump” 461 castings, 2.02” intake, 1.60” exhaust valves
Crank: Forged steel
L76 327 Engine Cam Specs:
GM #3849346 Cast iron, Duntov “30-30” cam
Operating RPM Range: 2800-6800 rpm
Camshaft style: mechanical flat tappet
Duration (@ .050 -inch lift): 254 int. / 254 exh.
Duration (advertised): 346 int. / 346 exh.
Lifters: Solid
Lobe separation (degrees): 114
Valve lash: .024 int. / .026 exh.
Valve lift (w/ factory 1.5:1 rocker ratio): .485 int. / .485 exh.
Induction: Holley 2818 600–cfm carburetor (first GM with a Holley Carb), aluminum dual-plane high-rise intake manifold.
327 L84 Engine Specs:
Horsepower: 375hp @ 6,200 rpm
Torque: 350 lb-ft @ 4,000 rpm
Compression Ratio: 11:1
Displacement: 327 cubic inches
Cylinder Bore: 4.001”
Stroke: 3.25”
Heads: Iron “double-hump” 461 castings, 2.02” intake, 1.60” exhaust valves
Crank: Forged steel
Cam- GM #3849346 Cast iron, Duntov “30-30” cam
Operating RPM range: 2,800-6,800 rpm
Camshaft style: mechanical flat tappet
Duration (@ .050-inch lift): 254 int. / 254 exh.
Duration (advertised): 346 int. / 346 exh.
Lifters: Solid
Lobe separation (degrees): 114
Valve lash: .024 int. / .026 exh.
Valve lift (w/factory 1.5:1 rocker ratio): .485 int. / .485 exh.
Induction: Rochester Ramjet mechanical fuel-injection
The L76 365 hp 327 and L84 variant are basically the same engine, the only real difference being the fuel-injection on the L84. These two engines are legendary around the world, partly for making the C2 Corvette the most powerful American sports car at the time. These engines are often referred to as the Corvette 365hp 327 and 375 hp Fuelie 327, or 327 fuel injection engines.
Corvette 327 Engine Build Ideas
So, what are the best heads for a 327 Chevy? The factory 461 iron casting SBC 327 heads, also referred to as “double-hump” heads, were the best that GM offered at the time. Though most of these heads had 1.94“/1.5” valves, the L76 327 and L84 327 versions were opened up with 2.02”/1.60” valves for better flow. Speedway has an entire section in their catalog for the L76 327 engine, including heads, intakes, and all manner of goodies. Whether you have 327 Chevy build, 350, 302, or another variant, Speedway Motors has the parts you need.
Best Heads for a 327 Chevy
One of the coolest offerings from Speedway for these 327ci engines is its aluminum 461 heads. These aluminum 327 Chevy heads match the original design that came out on the 1961 Corvette Fuelie, but instead of heavy cast iron, these are made from aluminum, shaving 40 pounds of unnecessary weight. They feature 180cc intake and 62cc exhaust ports, same as the original 461s, flowing an impressive 232 cfm at .500” lift on the intake, and 173 cfm at .500” lift on the exhaust side. To further the “L76 327 Corvette engine” look, the aluminum 461 heads have raised valve cover rails, so you can use roller rockers with the factory Corvette-logo valve covers.
The L76 and L84 variant of the 327ci SBC engine is a high-compression design, running 11:1 compression. This engine absolutely requires 93 octane fuel at a minimum. Without modern fuel injection controlling the timing, you simply cannot get away with running lower octane fuel. These engines also use solid flat-tappet lifters, which requires high levels of ZDDP in the oil, and periodic valve lash adjustments. So if you’re aiming to build a true clone of the L76 or L84, you need to keep this in mind. You could also build an L76 clone using the equivalent L76 327 cam specs but with hydraulic lifters, using this grind from Comp Cams.
327 365hp Parts List
Building a 327 clone of any code variant requires factory-looking parts. The 327s have some unique aspects to them, such as no bolt holes in the cylinder heads for accessories (all 1968 and earlier SBCs lack this feature), requiring special brackets. Speedway Motors has power steering brackets in two styles, depending on the water pump length. All 1967 and earlier 327 blocks are “small journal” blocks, using 2.30” main and 2.00” rod bearing bores, whereas the later ’68-’69 327s use 2.45” main and 2.10" rod bearing journals, which is the same a 350ci block. 327s and 350s have the same rod length measurements at 5.7”, but the bearing journals are different. 327s rev higher because of the shorter 3.25” stroke, while the 350’s longer 3.48” stroke makes more torque. If you have a 327 Chevy build, then you might want to check out Speedway Motors’ Vintage Top End Kit, featuring aluminum 461-style heads. If you want the old-school solid lifter cam, then this one from Comp Cams matches the factory 30-30 specs.
Corvette 327 engine codes have been used and re-used by GM, so it can be difficult to ascertain the exact specs for each engine sometimes. The L76 was reused in the LS-series engines, and while it isn’t the hottest LS engine, the LS-based L76 is a 360ci 6.0 liter V8 that develops 355 hp, so the 1964 L76 327 still beats it.
Want to learn more about the 1964 Corvette? Then click here to go to the GM Heritage Collection archives.