I agree that setting the gap to be loosely touching is best. I noticed that if the gap between the bumper and the cross member was set to 4mm on my car then it would not help in the unlikely chance that the rack rotated. On my car the gap between the pinion gear housing, at the face where the pinion shaft exits, and the cross member is less than 3mm, so that would hit before the bumper did. See the area pointed to by the red arrow in this picture.

I am glad I read this post.

 

I forgot I needed the rubber block so I made a mold for one today.

on my 72 the bumper is touching the crossmember

Where can I find this in the Service Manual? I think I am blind.

32 minutes ago, JagoBlitz said:

Where can I find this in the Service Manual? I think I am blind.

It's not mentioned in any of the manuals. The later 280Z manuals show it on some diagrams, but not further information about positioning and purpose of the bumper stop.

Here is a screenshot of the 1977 280Z manual out of the downloads section on this site.

 

Ah, okay. So I am only half-blind.
Thank you.

11 minutes ago, JagoBlitz said:

Ah, okay. So I am only half-blind.
Thank you.

Lol. You're not blind. It's something that seems to have been forgotten by the designers and thats why there is so much discussion about how to install and adjust it in this thread.