What are these screw holes for?

[nelso419]

[grayman_TT]

Those are for throttle spring covers.

[nelso419]

Thanks, now I just have to find some that aren't aftermarket or OEM jspec.

[nelso419]

How about the one hole in the first picture to the left of the plenum, in the black metal plate.

[nelso419]

Does anyone know why when you google image 300ZX engine, none of them seem to have the throttle covers? Do they all break off or something?

[itsa300zx]

Only the infinity j30 came with Oem spring covers.

[nelso419]

Ahhhh, I forgot that there are cars that exist other than mine.

[DCaff300ZX]

Those are indeed throttle spring covers, and would work with the J30 covers I believe. I was able to install the J30 covers which IMO are nicer than the other units available (larger, cover things better) but my TT did not have the two mounts on the drivers' side that you have- which would be perfect to mount it instead of the juryrig I had to make.
You can get them fairly reasonably from Concept Z or Z-1, and are a nice addition to the engine covering the unsightly rusting/peeling springs.