When is a small block a big block?
01-09-2009, 07:26 PM
#1
Le Mans Master
Thread Starter
When is a small block a big block?
Excuse my ignorance but I never did understand the differences. What determines when an engine is a either a small block or a big block? Is it displacement?
01-09-2009, 07:40 PM
#2
Race Director
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Location: Phila Suburbs 2023 C8 & 2013 650ix
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The small block Chevy engine is based on the original designed 1955 V8 265 cubic inch engine that had a measurement of 4 inches between the center of pistons. All of the engines in the C6 line are based on that dimension are defined as small block although the displacement goes from 364 cu in to 427 cu in. All V8 Chevy engines that have a larger dimension between center of pistons are big block. At least that's my understanding.
01-09-2009, 09:10 PM
#3
Le Mans Master
The small block Chevy engine is based on the original designed 1955 V8 265 cubic inch engine that had a measurement of 4 inches between the center of pistons. All of the engines in the C6 line are based on that dimension are defined as small block although the displacement goes from 364 cu in to 427 cu in. All V8 Chevy engines that have a larger dimension between center of pistons are big block. At least that's my understanding.
And to answer your original question: When is a small block a big block? The answer is never. You can actually take a small block up to some pretty large displacements, over 500 cubes even though most people say you shouldn't exceed 454.
01-09-2009, 09:25 PM
#4
Safety Car
The Gen 0 thru 3 the small block has a bore spacing of 4.40" the Gen 1 & 2 Big Block has a bore spacing of 4.84"
The only major parts that interchange between the two is the oil pump/lifters/distributor.
There is no 'big block LS' just large cubic inches.
While the "W" motor, 348/409, has the same bore spacing as the big block, it generally isn't refered to as a big block. With some minor machining the big block crank will fit in the W motor, but that's all.
The only major parts that interchange between the two is the oil pump/lifters/distributor.
There is no 'big block LS' just large cubic inches.
While the "W" motor, 348/409, has the same bore spacing as the big block, it generally isn't refered to as a big block. With some minor machining the big block crank will fit in the W motor, but that's all.
01-11-2009, 07:47 AM
#6
The Gen 0 thru 3 the small block has a bore spacing of 4.40" the Gen 1 & 2 Big Block has a bore spacing of 4.84"
The only major parts that interchange between the two is the oil pump/lifters/distributor.
There is no 'big block LS' just large cubic inches.
While the "W" motor, 348/409, has the same bore spacing as the big block, it generally isn't refered to as a big block. With some minor machining the big block crank will fit in the W motor, but that's all.
The only major parts that interchange between the two is the oil pump/lifters/distributor.
There is no 'big block LS' just large cubic inches.
While the "W" motor, 348/409, has the same bore spacing as the big block, it generally isn't refered to as a big block. With some minor machining the big block crank will fit in the W motor, but that's all.
Flat tappet lifters will interchange, roller lifters won't.
The "W" motors have always been referred to as a big block, they are called "Mark I" big blocks. There are no Gen 1 or 2 big blocks either, the progression is Mark I, II, III, IV, Gen 5, 6, and 7. Here's a good link on big block history:
http://reviews.ebay.com/Big-Block-Ch...00000001563647
01-11-2009, 07:56 AM
#7
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The Gen 4 small block has a bore spacing of 4.4" too.
Flat tappet lifters will interchange, roller lifters won't.
The "W" motors have always been referred to as a big block, they are called "Mark I" big blocks. There are no Gen 1 or 2 big blocks either, the progression is Mark I, II, III, IV, Gen 5, 6, and 7. Here's a good link on big block history:
http://reviews.ebay.com/Big-Block-Ch...00000001563647
Flat tappet lifters will interchange, roller lifters won't.
The "W" motors have always been referred to as a big block, they are called "Mark I" big blocks. There are no Gen 1 or 2 big blocks either, the progression is Mark I, II, III, IV, Gen 5, 6, and 7. Here's a good link on big block history:
http://reviews.ebay.com/Big-Block-Ch...00000001563647