OLDS Dx build

[fleming442]

The 330 and 425 cranks are steel, not iron. I'm not 100%, but a big block and D or DX have 3" mains vs. the small block 2.5"(?). So, to put a big block 425 crank in to fit the mains, the counterweights get turned down to fit clear the bottoms of the skirts. I have no idea how much stroke you can fit. My 468 has a 4.24" 425 crank on a Ch*vy pin (2.1 vs 2.2?).

 

[olds307 and 403]

The 425 crank is still plenty strong cut down, I think 4" is close to max stroke in a SBO. But a ton of work and Mallory go into to fitting the 425 crank in a 350 diesel block, even though they both have 3" mains, it won't be much cheaper and still not as strong and heavier than the 5140, let alone the 4340 billet crank.

 

[Nitro442]

Anyone know the difference in these dx blocks? About all I can find is the f2 is the earliest and highest nickel content. The other two blocks are f4 and f5. All dx blocks. But my question are of the numbers stamped by the timing chain cover...

 

[Nitro442]

Anyone know the difference in these dx blocks? About all I can find is the f2 is the earliest and highest nickel content. The other two blocks are f4 and f5. All dx blocks. But my question are of the numbers stamped by the timing chain cover...

Mainly the GM5 on two of the blocks but not the other

 

[fleming442]

I'm pretty sure the "nickel content" myth is just that- a myth.
No idea about the codes...

 

[Nitro442]

I'm pretty sure the "nickel content" myth is just that- a myth.
No idea about the codes...

Most likely is a myth but they do say the earlier blocks were a higher nickel content lol

 

[64nailhead]

Until this thread, I'd never knew the DX (diesel) block is preferred for anything. I know that engine platform can accurately be described as non-preferred. But these blocks appear to have a very large bore spacing that is made up with ALOT of material. So is it safe to infer that these are very very very stable bores? I'll answer/guess yes.

What is the deck height? Bore and stroke? Are these 5 main blocks? Are there any stock dimensional forged rotating assemblies or crank options available through the aftermarket? What heads fit them (aluminum)?

The reason for the questions is that a big bore spaced block is what is found in the aftermarket for blocks, i.e Dart, Brodix, etc. I do understand about increasing the cubes with a 425 crank, but a lower rod to stroke ratio is much easier to make more power with in a non NA build. And by easier, I'm implying cheaper. This is becoming more and more prevalant in the world of boost and boosted x275 cars.

Just curious and interested as these blocks, despite not being readily available, are relatively inexpensive when found/available.

 

[olds307 and 403]

With the exception of the 3 inch mains, they have nearly identical dimensions to an Olds 350 with much thicker main webs. A gas Olds 350 block can be bored .100 over, so already has thick walls. It was GMs best factory 350 IMHO. There is a 5140 or 4340 Billet steel aftermarket 4 inch stroke crank that is lighter and stronger than the factory 330 forged crank. You just need the readily available 4 bolt main 2.5 inch main caps with bearing spacers in the block. Both are proven under serious power. Mark Remmel (Cutlassefi) brought this crank to the market. He is currently looking to do a 3 inch main version for a direct fit in the diesel block. You think the diesel block is strong, Olds had a Nascar block. Super thick main webs, 2.5, 2.75 and 3 inch mains, some had siamese bore spacing like the 403, allowing a 403, 4.350 bore size with super bottom end strength. The new Rocket Racing block is basically a tall deck version of the Nascar block. Olds bore spacing is 4.4 inches, RR block is siamese and BBO allows dam near a 5 inch stoke in the factory BBO height, tall deck block, allowing 560 ci in the new Rocket Racing block. They even have a compact graphite option for the block. It is made at the same place as the Dart blocks.

 

[rogue_ryder]

Just curious and interested as these blocks, despite not being readily available, are relatively inexpensive when found/available.

Last time I was at one of the yards off I-25 near Colorado National Speedway there were 2 or 3 Olds 350 Diesels in there! The only thing that keeps me from building one is not the cost of acquiring the core but the machine work and parts and up until now finding a 425 crank (The 330 crank with spacers works but then you're leaving a lot of Cubes on the table). IMHO There's no point in doing a DX build for anything other than Big CI and an all out build. I'd say you're probably looking at $10K in parts and Machine Work unless you get really creative or have parts laying around. The cost is probably the biggest reason you don't see DX builds often, you can build a decent SBO 350 for 1/2 the money (but probably 1/2 the power too LOL).

 

[fleming442]

Less cubes+more beef=high revs+more boost