Hello, i would like to ask you how to identify a 455 big block, i think mine is a 455 since its blue but i just wanted to be sure. And if someone can give its specs that would be awsome. (1974 442)

 

455s have casting number 396021F on the shelf behind the water pump.

 

Biggest sign is left of his finger, that raised piece of metal is only on a big block, small block is smooth all the way across.

 

This is true but big blocks came in 400 425 and 455 CID so the numbers there and the numbers on the block below the head by Number 1 spark plug on the pad there are also important.

 

And two different versions of the 400 CID engine at that. The casting number is very important to identify which BBO is which.

 

Actually there are THREE different 400 blocks (B, E, and G), two different 425 blocks (A and D), and three different 455 blocks (F, FA, and the elusive L). Of course, the B and E blocks are short-stroke 400s and the G is the long-stroke 400.

 

Don't mean to hi-jack but what are the differences between A and D 425 blocks?

 

In reality, nothing meaningful. The A-block is 1965 only. The D-block is 1966-67. All A-blocks used a 45 degree lifter bank angle and 0.841" lifters. All D-blocks used in RWD applications (non-Toronado applications) were also 45 deg and 0.841". The 66-67 D-blocks used in Toros got the 39 deg lifter bank angle as used in the 68-90 motors but the uncommon 0.921" diameter lifters.

 

Thanks Joe. Your knowledge knows no bounds!