The heat shield under the EFI intake are 8x1.25. There are no M8x1.5 threads anywhere on a Z. 

The four SU heat shield bolts are M6x1.0. 

3x0.5

4x0.7

5x0.8

6x1.0

8x1.25

10x1.5 on the block

10x1.25 any suspension

12x1.25

and a few 14mx1.5, M16x1.5,. 20x1.5, 22x1.5 for good measure

A few oddball SAE. Seat belt bolts, ;hood bumpers, door lock buttons, blah blah blah 

And stupid tiny choke knob that are M2.5 or something silly

Edited October 21, 20204 yr by zKars

Ooops.     Sorry, I gave you the wrong answer on that one. Glad @zKars was there to supply the correct answer.

Thanks for the link to your other thread. I didn't look at it yet, but will when I get a chance.

1 hour ago, Captain Obvious said:

Ooops.     Sorry, I gave you the wrong answer on that one. Glad @zKars was there to supply the correct answer.

Thanks for the link to your other thread. I didn't look at it yet, but will when I get a chance.

Well the funny thing is, I wrote that thread about a year ago, then lost my password and never went back! 

First of all, thanks to @zKars for the fastener lessons. I was able to get some M8X1.25 by 10mm today to fasten the heat shield to the bottom of the manifold. I'm still probably going to put some heat reflective tape on the bottom of the heat shield but it's mounted up for now.

Second, the ETB 350Z came today and it is in really good shape. But... 

Nothing can be easy with this project so I'll have to fabricate a spacer to put this on the L6 manifold. Oh well... I understand the matching pedal will mount to a vertical firewall so there is that! 

LOL! So the mounting pattern is not the same. Bummer. I was trying to dig into that for you, but didn't come up with anything concrete in time.

So is there enough meat to file the holes on the TB so you can get it to mount? Or is it just too far off?

9 hours ago, Captain Obvious said:

LOL! So the mounting pattern is not the same. Bummer. I was trying to dig into that for you, but didn't come up with anything concrete in time.

So is there enough meat to file the holes on the TB so you can get it to mount? Or is it just too far off?

Looks like there is enough to work. I will run it by Rex, a 510 guy and machine shop manager Monday. It looks like it’s aftermarket because all the 350Z ETB’s I’ve seen have “Hitachi Nissan” cast into them. This one, nothing. We can try to make it fit and if we break it, we chuck it!

Ok, even though I'm retired with the Covid situation, my anesthesia skills are in demand so I do a day or two a week of work at the hospital. The reason that is relevant is that I have not had time to examine the 350Z throttle body to see if I can just redrill it or if I need an adapter plate to make it work. My conclusion? I think I need an adapter plate. And frankly, as long as I have to make an adapter plate, I think I'll just make one that accepts the aftermarket 350Z 75mm ETB's that are out there.

I just don't think there is enough meat in the stock 350Z ETB to drill it out for the bolt pattern on our L28 intakes. 

Edited October 25, 20204 yr by conedodger

Gotcha. Of course it's impossible for me to tell from just the pics, but from my end of the screen it doesn't look like there's enough meat.

But do you really need 75mm? Is there any downside for "too big"?  I'm thinking that because of the inherent non-linear nature of butterfly valves, that it could be twitchy at low throttle positions or something?

17 minutes ago, Captain Obvious said:

Gotcha. Of course it's impossible for me to tell from just the pics, but from my end of the screen it doesn't look like there's enough meat.

But do you really need 75mm? Is there any downside for "too big"?  I'm thinking that because of the inherent non-linear nature of butterfly valves, that it could be twitchy at low throttle positions or something?

Here's my thoughts on the larger throttle plate. @duffymahoney is using ITB's and has more throttle plate square CM opening up all at once. I suspect that you're right and there is no advantage and perhaps a downside to too much throttle plate. I have to research more. 

If you find any good info on the butterfly sizes, let us know. And good luck with the project.

Will do @Captain Obvious, I am researching with the Haltech site on that. It is 'monitored' by the Haltech guys, but most often they don't do the answering of questions. Because of that, you don't know what you're getting. After all, there are far more experts on the internet than there are in the world by about 5 times! 

What I could use now, is a 2D file of the inlet side of the '75 intake manifold. The reason I need it, is because I feel I'm going to have to make an adapter to mate whatever Electronic Throttle Body to the factory manifold. My son, who is an architecture student graduating in May of next year has told me he can make me a working drawing that I can send to my friend Larry who is a CAD Machinist to make 2-3 adapters. (I can't be the only one who wants DBW right?) 

Will do @Captain Obvious, I am researching with the Haltech site on that. It is 'monitored' by the Haltech guys, but most often they don't do the answering of questions. Because of that, you don't know what you're getting. After all, there are far more experts on the internet than there are in the world by about 5 times! 

What I could use now, is a 2D file of the inlet side of the '75 intake manifold. The reason I need it, is because I feel I'm going to have to make an adapter to mate whatever Electronic Throttle Body to the factory manifold. My son, who is an architecture student graduating in May of next year has told me he can make me a working drawing that I can send to my friend Larry who is a CAD Machinist to make 2-3 adapters. (I can't be the only one who wants DBW right?)