Hey guys I am pretty new here. I got my hands on a 78 GMC Sierra with a 350 5.7l Diesel in it. If I remember right they are the gas block converted over to Diesel. Well long story short the engine got hydro locked. Now I'm in the market for a replacement engine and was wondering what you guys think a decent replacement would be. I could go the gas route or continue using diesel either option is good for me. I've looked for a Olds 350 5.7 Diesel and couldn't find one. Let me know what you guys think.
I used to think the same about the Olds 350 diesels, and my old man told me when I was a kid that they were based on the Olds 350 gas, but that's a fallacy. The only thing they share is the same bore and stroke dimensions. The compression ratio of the diesel is nearly triple that of the gas version, and the gas block would fail under that amount of stress. That being said, unless yours is a later model that was swapped in, that's the first year for the Olds diesel. They fixed the problems later on, and if you could find a later one, that would work. However, if you want to be back on the road as soon as possible, a 6.2/6.5 would be the answer, I think. Not the most powerful, but you can build the 6.2 to be respectable. Other than that, everything else isn't gonna be a plug and play swap in the diesel department. The Cummins 6bt is the crown jewel there, but that's not going to have you on the road as soon. You also have the unique opportunity to swap in a gasser and still be exempt from emissions scrutiny, right? If so, the 350 and 400 SBCs would be my votes for gas swap candidates.
