Chevy SBC 350 Firing Order and other facts about the engine

Learn about the Chevy SBC 350 firing order, engine design, and history

The Chevy 350 is an iconic V8 engine that was part of the Chevrolet small-block engine family, a series that dates back to the mid-1950s. It debuted in the 1967 Camero and powered the Corvette, Caprice, and many other GM brands like Buick, Cadillac, and Oldsmobile. This article covers the Chevy 350 firing order, but to get the actual engine specifications like bore, stroke, and horsepower by year and casting numbers, see this post.

Chevy 350 firing order

Chevy SBC firing order and engine layout

The firing order for the Chevy SBC 350 is 1-8-4-3-6-5-7-2

The cylinder numbering is 2, 4, 6, 8 on the left bank when viewed from the front (harmonic balancer) end, and 1, 3, 5, 7 on the right bank.

The distributor rotor turns clockwise when viewed from above and is the same layout as a breaker point or High-Energy Ignition (HEI) distributor.

Chevy 350 Build Specifications

The vast majority of Chevy 350 engines feature cast iron heads and blocks. However, there are a few exceptions, such as the Gen Two LT-1s, which had aluminum components, and the L98 engine found in the Corvette, which combined iron and aluminum components.

Regardless of the material composition, all Chevy 350 engines share the same bore and stroke measurements of 4 inches and 3.48 inches, respectively, resulting in a total displacement of 350 cubic inches.

First Generation variants

There were 17 variants of the 350 engine. The original 350 SBC was the L48, produced from 1967 to 1980. It featured these build specifications:

• 2.45″ main journals
• 2.1″ rod journals
• 3/8″ rod bolts
• 4 main bearing caps
• Reinforced block
• Mechanical cams until 1969 when hydraulic cams were introduced
• The Holly carburetor was replaced with the 4bbl Quadrajet in 1969
• Compression Ratio: as 1.25:1 from 1967 until 1971 when it was reduced to 8.5:1 to obtain better emissions.
• Horsepower: 300

The L46 variant was the high-performance version of the L48, with an 11.0:1 compression ratio and modified internals to produce 350 horsepower.

The LT-1 engine had high-performance cams, an 11.0:1 compression ratio, a 780 cfm 4-barrel Holley carburetor, and a high-rise aluminum intake manifold. The LT-1 delivered a maximum of 370 horsepower in the Corvette. However, it was detuned in 1972 for emissions reasons and H.P. was reduced to 255.

The L82 was equipped with the Rochester Quadrajet 4-barrel carburetor, a dual-plane aluminum intake manifold, a hydraulic cam, and forged aluminum pistons. In 1971, the L82 maxed out at 250 horsepower.

Second Generation SBC 350 Engines

In 1990, Chevy introduced the LT5 variant with different internals and a much different coolant flow pattern. Chevy engineers directed the coolant flow to the cylinder heads first and then into the block, just the opposite of previous designs. The change raised compression ratios, lowered combustion chamber temperatures, and reduced leaks due to fewer gaskets.

Chevy 350 Common Problems and Reliability

Overall, the Chevy SBC 350 is a reliable engine. However, certain variants have problems.

• Optispark distributor failures

The LT1 variant, for example, is known for the high failure rates of the Optispark Distributors. The distributor was designed with undersized ventilation that resulted in moisture buildup, corrosion, and early failure. Chevy enlarged the ventilation holes in 1994. But that didn’t stop the failures because the distributor was located at the bottom front of the engine, where it was exposed to water, dirt, and road grit kicked up from the street.

• Headgasket failures due to overheating

The  LT1 is known for head gasket failures from overheating

• PCV Valve Failure and Spark Plug Fouling

The PCV system is known for causing spark plug fouling. The fouling and resulting misfires caused spark plug and spark plug wire failures.

©, 2024 Rick Muscoplat