Is a Pontiac 400 and a 455 the same block?
No, the Pontiac 400 and 455 engines do not share the same engine block. While they are both large-displacement V8 engines produced by Pontiac, they have distinct differences in their engine block designs and specifications.
Pontiac 400 Engine
The Pontiac 400 is a V8 engine that was produced from 1967 to 1979. It had a displacement of 400 cubic inches (6.6 liters) and was available in various performance levels, ranging from the standard 265 horsepower version to the high-performance Ram Air IV model that produced up to 335 horsepower. The 400 engine block was designed with a 4.12-inch bore and a 3.75-inch stroke.,p>
Pontiac 455 Engine
The Pontiac 455 is a larger V8 engine that was produced from 1968 to 1976. It had a displacement of 455 cubic inches (7.5 liters) and was available in both standard and high-performance variants. The 455 engine block was designed with a 4.21-inch bore and a 4.00-inch stroke, making it a larger and more powerful engine compared to the 400.,
Key Differences
The primary differences between the Pontiac 400 and 455 engines are:
- Displacement: The 455 has a larger displacement of 455 cubic inches compared to the 400's 400 cubic inches.
- Bore and Stroke: The 455 has a larger bore (4.21 inches) and stroke (4.00 inches) compared to the 400's 4.12-inch bore and 3.75-inch stroke.
- Power Output: The 455 engine was generally more powerful, with high-performance variants producing up to 370 horsepower, compared to the 400's maximum of 335 horsepower.
While the Pontiac 400 and 455 engines share some similarities as large-displacement V8 engines, they have distinct differences in their engine block designs and specifications that make them separate and distinct engine models.
Is a GM 400 a small block?
And a small block chevy 400 is the siamese bore that was used by gm to achieve the larger bore and stroke combination specifically larger bore combination.
Was the Pontiac 400 a good engine?
That made the 400 the top engine in Firebird and GTO for many years as it received a wide range of high-performance cylinder heads and camshafts through various iterations of the Ram Air package. The most powerful version of Pontiac's 400 to ever reach production was the Ram Air IV.
Did GM make a 400 big block?
No - the small block was available in 400 CID - but the big block was never that exact size. 396 CID would be the most common engine “close” to that size - but the BBC also came in 402, 409, 427, 454……but not exactly 400 CID.
How much horsepower can you get out of a Pontiac 400?
Back in the day, the most powerful 400 (Ram Air IV) made by Pontiac put out 370 hp (GTO), so 512 hp is certainly a ton more performance; all in, it's a package that looks deceptively stock.
Is Pontiac 455 a big block or small block?
The original 1970 Pontiac 455 'big block' V8 was good for between 360 and 370 horsepower and 500 lb-ft of torque.
Can you make a 400 Pontiac into a 455?
Converting a 400 to a 455 is not a new development, although many myths and doubts have surrounded this modification for years. My success in perfecting this modification has made a lot of Pontiac gearheads very happy.
Are the Pontiac 400 and 455 the same block?
We took the question to David Butler of Butler Performance in Lawrenceburg, Tennessee, for his professional opinion. He advises, "With the exception of the mid- to late-1970s PN 500557 casting, we consider all Pontiac 400 blocks functionally identical. The 455 blocks from 1970 to 1976 are also functionally identical.
Did Pontiac have a 400 big block?
Pontiac differed from other GM Divisions and most other manufacturers in producing only a single sized V8 casting, rather than adding a larger big block to its line-up. The external dimensions of all their V8s, from 326–455 cu in (5.3–7.5 L) were the same.
Are the Pontiac 400 and 455 block the same?
Functionally, these blocks are very much the same, with only minor structural differences, and virtually all were drilled and tapped for four-bolt caps (though only the 19701972 455 H.O. engines were equipped with them).
How much HP can a 455 big block handle?
The 455 offered between 310 and 400 hp, but it was the 500 lb-ft of torque that really made it a star. Most notably it was used in the iconic Olds 442 muscle car, but it also found its way into the family-friendly Delta 88 and several luxury sedans.
