This if from a book, Air Research T-04 and T-4B series. Air Research is Garrett and the T4 is similar to the T-3.T3

You are supposed to use a new lock nut. The T4 and T3 turbos are known to speed shops as variations are used on gassers. A likely local source of a new nut.

The instructions are: Install the compressor impeller. Use a twisting motion; bottom it on the thrust collar.

There is no publishing date on the Manual but in the past they used a washer head nut that was a nylock type nut. Not sure what they currently use. So the instructions reflect that.

Washer face of the locknut and the compressor impeller must be smooth and clean. Lightly oil the washer face area and the threads. Install the locknut and tighten to 18-20 Lb in. (More frequently known as inch pounds.)
Use a sliding T handle and further tighten the locknut another 90 degrees.

The use of the T handle is so you can provide more even tightening that useing say a ratched wrench would do because the ratchet is going to pull on one side more then the other.

So that is what is in the manual.
However, when I researched it on the internet you find at least 4 different instructions on tightening the shaf nut. Apparently in practice they all work because I did not read of anyone's shaft nut comming loose.

My home computer would not open up the document that was posted so I don't know if the instructions in the document are the same or not.

The Manual I have is labled Fiat-Allis Turbocharger (Airesearch T-04 and T04B series). Fiat Allis used to be known as Allis Chambers. So this would be a book equipment that usese the (Airesearch T-04 and T04B series) turbochargers.

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84 300D, 82 Volvo 244Gl Diesel