GM 350 vs Olds 350

[ScottyB]

Ok, technically they are both GM products. I thought I had heard somewhere that there were differences between a GM 350 and an Olds 350 though. Reason I ask is my son may have tracked down an Olds 350 that we can just pick up and haul off. Sounds like a fun project and may find a home in my 77 C30 as a replacement for the 454 that is in there right now.

 

[1987 GMC Jimmy]

As long as it's not a diesel... Yikes.

 

[HotRodPC]

As long as it's not a diesel... Yikes.

Even the Diesel DX blocks are the ****. In this case he's talking about it won't be. Don't anyone EVER trash a Olds 350 Diesel DX block. You can easily put gas heads on it, and you have 1 strong ass bottom end as the crank journals and mains are bigger. Remember, the diesels just had head problems. Bottom end is great. There are even stroker kits for the DX blocks to make big cube inch Olds small blocks.

 

[HotRodPC]

Ok, technically they are both GM products. I thought I had heard somewhere that there were differences between a GM 350 and an Olds 350 though. Reason I ask is my son may have tracked down an Olds 350 that we can just pick up and haul off. Sounds like a fun project and may find a home in my 77 C30 as a replacement for the 454 that is in there right now.

GM 350 is usually a Chevy 350. If it's a "GM" Olds engine, chances are it's a 307. It was used in many Cads, Buicks, Olds etc. Nothing spectacular but a good solid reliable smogger engine. Not what I'd want for a truck at all. And if it is indeed a "GM" Olds 350, chances are it's a 77 or later 350 block. The 77 and later had Windowed main caps. Meaning, they're not solid like the 76 and earlier main caps. They took part of the meat out of the main cap. Not good for high rpm at all and prone to fail. If it's a 76 and earlier full main cap 350 it's rock solid.

Truth be known of all the GM 350's, Olds, Buick, Pontiac, Chevrolet, Olds is said to actually be the best one with a square bore x stroke combo.

 

[HotRodPC]

This is why I'd like to find a DX Olds Diesel Block.


They are the same only to the extent that the bore and external interfaces are the same. The diesel block is significantly heavier duty, with much thicker cylinder walls, main webs, etc. In addition, the diesel uses the big block's 3" main bearing size as opposed to the small block size. As a result, the diesel block is much heavier than a gas 350 block.

Other differences include much beefier connecting rods, a significantly higher compression ratio (what, like 22:1?), and obviously unique heads and intake with injectors. Also, the diesel uses a vacuum pump to power accessories, which takes the place of the unneeded distributor (or was that where the injector pump went?).

 

[ScottyB]

I'm still waiting for the details on this, but it sounds like it is all torn down waiting for assembly. The kid was going to use this for his senior project and then something changed so it has just been cluttering his dad's garage ever since. If it is torn down, this will be perfect. My son is starting school this fall to become an automotive tech. This would give him an engine to build up even if we don't put it in anything.