720 Diesel Project

[Jarhead00763]

My fiance has a 1985 Datsun/Nissan 720 King Cab ST that is in pretty bad shape, so we are rebuilding it with a diesel engine and manual transmission. I'm not familiar with what kind of diesel engine I can use with a manual in this particular truck. Any ideas?

[datzenmike]

The 720 came with two diesels over the years. The SD22 till '83 and a slightly larger SD25 after. There were no automatic diesels only 5 speeds. They run ok and get good mileage but they don't have much power. I would stick with the Z24 gas engine that's in it

[Charlie69]

The diesels also came in the Maximas with a diesel and automatic.  I have seen 2 diesel Maxima wagons that were diesel and automatic.

 

Wayno is the resident diesel guru around here.

 

Myself I would stay with a z24 or do a KA24.

[datzenmike]

the LD28 would be ungodly heavy and it's way too long being a 6 cylinder.

[wayno]

Unless you already have the diesel engine/transmission I would not bother, they do not have much power, the  SD22 only has 61hp, and the SD25 has 71hp, neither are common, also the engine mounts are in a different place than the Z24 engine mounts, it will be a major project to convert to a diesel in a gas truck, and you will also need the diesel wiring harness complete with all diesel gadgets, otherwise you will have to use a choke cable to start and stop the engine after using a button of some type to warm up the glow plugs.

The Z24, KA, or even a VG30 would likely be easier to get on the road, especially the Z24 as that is likely what is/was in it.

The Nissan diesels that came in the 720 should be uncomplicated as the diesel engines themselves are simple, but the way Nissan did them with the vacuum throttle in this country is very complicated electrically to start and shut them down, but the inline injection pump does last a very long time considering how long the VE type pumps last in other countries.

I turbocharged my SD series engines in my trucks, but that is just another layer of complication.

If you already have the engine/transmission, you are welcome to come over to my house and look at what is involved for a diesel conversion, I live in Vancouver WA and I have a lot of what you need to do it.

Edited September 14, 2018 by wayno