Chevrolet cars and engines are topics that many people are interested in because they want to improve their driving performance and safety.
On the current trend, a lot of car owners care about small block engines, including 350 and 400 ones.
These two often make us confused due to their similar block design. So, what are the differences between 400 small block vs 350?
If you want to find out the answer, keep reading this article. We will provide all the necessary information to compare them.
An Overview Of A 350 And A 400 SBC Engine
A 350 Small-Block Engine
The Chevy 350 engine, the most well-known small block V8 engine in GM’s lineup, is regarded as one of the greatest engines of the 20th century.
The 350 is famous for dependability and usage in a range of applications, including boats. Many users have a high evaluation for its longevity, quiet operation, and performance.
The 350 cubic inches (5.7 liters) small block V8 base engine of the Chevy 350 had a 3.48-inch bore spacing and stroke ratio of 4.00.
HP ranges from around 145 to more than 370 depending on the manufactured year, make, and model of an automobile.
This engine, which has a maximum torque level of 380 lb ft, is excellent for towing but has poor fuel efficiency and may need premium gasoline based on the compression ratio.
A 400 Small-Block Engine
The 400 small block engine was designed to be utilized largely in Chevy’s bigger passenger vehicles and light-duty trucks because of its high torque and low performance.
While having internal differences, the overall design was the same as preceding small block Chevrolet engines and included many outward characteristics and dimensions that were identical.
With modifications, the 400 has established a reputation as a potent performance engine.
The 400 small block has a displacement of 400 cubic inches. It can withstand a lot of torque since it is composed of cast iron, which makes it quite sturdy.
Iron castings are also used to create cylinder heads. However, they are frequently known to be made of lightweight aluminum in race applications to boost performance.
The 400 engine was built to generate strong torque at low RPM. This makes it a great application for pickup trucks and SUVs.
Additionally, it offers a two-barrel carburetor and a four-barrel carburetor. If you need greater performance, the 4-barrel carburetor is ideal.
The 400 small block has around 265 horsepower. Yet, it generated roughly 150 horsepower at the wheels.
What Are The Differences Between 400 Small Block Vs 350?
A 350 small block and 400 have the same block design. Thus, almost all accessories can fit these two production engine.
The most-mentioned difference between them is their casting numbers and how they are balanced. Also, the RPM of the Chevy 350 engine will be substantially greater than that of the other.
How to tell difference between 350 and 400 small block? Let’s take an in-depth look at the comparison of 350 vs 400 SBC:
Casting Numbers
On the block or head of an engine, manufacturers stamp identification markings known as engine casting numbers.
Making use of the casting number guarantees choosing the right components. Behind the block fitted to the transmission, you can see the cast numbers on the engine blocks.
Pour the degreaser into the wire brush to clean up the block to measure these numbers.
There are just three unique numbers on the Chevy 400 engine, which are 330817, 3951509, and 3951511.
The majority of the 1511 casting numbers were four-bolt mains. The most common two-bolt mains are the 0817 and 1509.
The two-bolt mains contain far more nickel in the webbing than the four-bolt blocks, which makes the 400 block stronger than the 350.
Head Gaskets
Because the cylinders on the 400 were siamesed, it called for “steam” holes, heads, and head gasket to assist reduce “hot-spots” in the cooling system at the position above the siamesed cylinders.
This made the 400 different from the 350 small block.
If a 400 block uses heads or head gaskets with no “steam” hole, overheating and damage are likely to occur.
Flexplate And The Inch Bore Spacing
A 400 cubic inch engine features a larger bore (4.125 inches) compared to the Chevy 350’s 4-inch bore spacing. The 350 features a shorter stroke of 3.48 inches, whereas that of the 400 is 3.75 inches.
Moreover, the 400 has 5.565-inch rods, and the previous SBC engine offers 5.7-inch rods (a higher compression engine).
Additionally, the major crankshaft of 400 small-block engines was externally balanced and had a diameter of 2.65 inches, while the 350’s main journals had a diameter of 2.45 inches (on the flexplate and harmonic balancer).
Frequently Asked Questions
How Much HP Can A 400 Small Block Make?
When timing and jetting were optimized, the engine dyno shows that this product produced 458 lb-ft of torque at 4,000 RPM (pretty low), but the 400 Chevy small block horsepower only reached 401 at 5,400 RPM.
What’s The Difference Between A Small Block And A Big Block?
Small and big blocks, known as overhead valve engines, are frequently used to describe V8 pushrod engines. A big-block engine is noticeably bigger than its small-block in this engine family.
In addition to the size, the real distinction between the two is more about displacement, stroke ratio, and bore.
Big-block engines often have displacements of over 400 cubic inches, whereas small-block ones typically have a lesser displacement.
However, there are a few exceptions to that generalization because nothing in the automobile world can be that straightforward.
Due to the way the engine’s valves are built and how its cylinders are arranged, some engines with enormous displacements are commonly known as “small blocks.”
Indeed, the Chevy 396 is an illustration of an engine that, while having a displacement of less than 400 cubic inches, is known as a “big block” because of its design.
Conclusion
This article has provided all the necessary information about 400 and 350 engines. Moreover, you can get hold of some primary differences between 400 small block vs 350.
Depending on your car and your requirements, you should read and understand the specs of these two to choose the most suitable engine.
A proper one can help you improve your driving performance and safety.
Moreover, remember to maintain the engine regularly to prevent some engine-related issues, such as Chevy knock sensor bypass.