The D0VE-A block comes in two primary configurations: 2-bolt mains and 4-bolt mains. The reason for the D0VE-A block's popularity is its thicker main webbing, and also because the main webbing is fully machined from the main caps all the way out to the oil pan rail, which facilitates the conversion of the 2-bolt main blocks to 4-bolt mains. (The standard-webbed passenger car blocks have a section of main webbing between the main caps and oil pan rail that remains as-cast/unmachined.) 4-bolting of the 2-bolt D0VE blocks is usually executed on mains 2, 3, & 4, while mains 1 & 5 remain in their 2-bolt configuration.
There is sometimes talk of D0VE-A blocks that have "Boss 429 bulkheads," and people often ask what that means. In short, it means that when some of the D0VE-A blocks were originally cast, some (but not all) of the casting patterns used for the D0VE-A blocks made use of the front and rear sections of a block pattern originally used for casting the C9AE Boss 429 blocks. The result is that some D0VE blocks were cast with Boss 429 block features front & rear, and some of those specific features of the Boss's block pattern are advantageous on the D0VE-A castings for some applications.
Specifically, the C9AE Boss 429 blocks were 4-bolted from the factory on mains 1
, 2, 3, & 4 (not just 2, 3, & 4 like the SCJ blocks). In order to secure a 4-bolt main cap to the number 1 main webbing on the Boss 429 block, it was necessary to add more block material at the outer reaches of the number 1 main web so as to accomodate the outer main bolts (of the number 1 main's 4-bolt main cap) to be added into the block. Another nice feature is that the number 1 main saddle has significantly more material around its perimeter. Together, these two added details of the Boss bulkhead D0VE blocks (the additional main webbing material and
additional main saddle material) make 4-bolting the number 1 main of the D0VE block (with Boss bulkheads) more inviting and also improves structural integrity in both the main saddle and 4-bolt main cap securing at the cylinder block.
What's the advantage? For people running passenger car blocks at the lower horsepower levels that most use them, it might not offer any measurable benefit. But for higher horsepower applications the Boss bulkhead feature might be sought after by those who run a Roots-type blower which has its drive belt tugging on the crankshaft snout (and thusly, the number 1 main saddle) and/or who want to 4-bolt the number 1 main cap. Or, it might be sought after by those who's power take-off is at the snout instead of the flywheel, such as a snout-driven v-drive speed boat or some other application.
How can you identify whether an fully assembled 429/460 engine with a D0VE-A block has the Boss bulkhead feature or not? There is one external feature that denotes a D0VE-A block that has the Boss bulkheads, and that is the "A" on the raised square pad located at the front of the driver's side cylinder bank:
Please note that while all "A" marked blocks have Boss 429 bulkheads, there are also Boss 429 bulkhead D0VE blocks that don't have the "A" at the front of the block. We have seen them both ways (with and without the "A"). What this means is that if you are scouring a junk yard and find an assembled engine that has a D0VE-A block with the "A" on the raised square pad, you've just found yourself a D0VE-A block with a Boss 429 bulkhead. If the "A" is not there, then it may or may not
have the Boss bulkhead (engine disassembly is required to visually verify the existence of the Boss bulkhead features). The "A" is basically a guarantee that the Boss bulkhead feature is there.