Bolt spacing where the bellhousing mates to the back of the engine.
The difference is in the design of the head. Also due to the head design, the physical size of the motor is larger even if CID (displacement) is identical. The best visual example I can think of is Ford 351 windsor which was a small block: http://www.mustangsteve.comW351_65.jpg and a Ford 351 Cleveland which was a big block: http://thunder-performance.com/images/Tony\'s%20351%20Cleveland%20(1).JPG Generally you can tell the difference by looking at the valve covers. if they are long, narrow and rectangular, it's a small block. If they are fat squat and irregular shaped, you're looking at a big block. There are other differences too, for example bore and stroke. A small block generally has a shorter stroke and is thought to rev higher, whereas a big block has a longer stroke with more torque. There are other disputed difference between a small and a big block. And for the most part, you can simply tell by the displacement. Generally, anything larger than 366 CID is a big block.
The 390 Ford motor is an FE block and was made as a Big Block only. The small block or Windsor motor could be bored and stroked to have 390+ cubic inches. To build a stroker motor you have to do extensive machine work and parts matching. That process usually involves large amounts of money.
The difference is in the design of the head. Also due to the head design, the physical size of the motor is larger even if CID (displacement) is identical. The best visual example I can think of is Ford 351 windsor which was a small block: http://www.mustangsteve.comW351_65.jpg and a Ford 351 Cleveland which was a big block: http://thunder-performance.com/images/Tony\'s%20351%20Cleveland%20(1).JPG Generally you can tell the difference by looking at the valve covers. if they are long, narrow and rectangular, it's a small block. If they are fat squat and irregular shaped, you're looking at a big block. There are other differences too, for example bore and stroke. A small block generally has a shorter stroke and is thought to rev higher, whereas a big block has a longer stroke with more torque. There are other disputed difference between a small and a big block. And for the most part, you can simply tell by the displacement. Generally, anything larger than 366 CID is a big block.
Big block
The Windsor is a small block, basically an enlarged 289. The Cleveland is a big block, more high performance. You can tell the difference from the outside by looking at the valve cover. The Cleveland has 8 bolts securing it down * the Windsor has 5. Also the thermostat cover bolts to the block on a Cleveland and to the intake on a Windsor. Neil
No. The 302 is a small block only. However, the 351, came as a Windsor, or small block, and a Cleveland, which was a big block...
351 modified has a 400 big block housing where the Clevelnd does not.
The Windsor is a small block, basically an enlarged 289. The Cleveland is a big block, more high performance. You can tell the difference from the outside by looking at the valve cover. The Cleveland has 8 bolts securing it down * the Windsor has 5. Also the thermostat cover bolts to the block on a Cleveland and to the intake on a Windsor. Neil
300 cyl engine not a small block at all
No, because the small block Chev fits so well
One has a longer stroke than the other.Crank shafts ,and rod lenghts,the only difference that I know of.Same block,ect .
That Boss 302, was a pretty amazing motor.