76 280Z Throttle Body bolt spacing

[wheee!]

Hey guys! I am away from the car at the moment and I wonder if anyone knows the throttle body bolt spacing for the N42 intake manifold on the 76 280Z. I am looking at an aftermarket 70mm throttle body with 65mm bolt spacing. I seem to remember the stock throttle body was 60mm...?

Can anyone help? @Captain Obvious perhaps?

Thanks!

Edited October 6, 2023 by wheee!

[Zed Head]

You could go to an auto parts store and measure or buy a gasket.  Don't you have a manifold to measure from?

https://www.oreillyauto.com/search/v/a/6635/automotive-car-1976-nissan-280z?q=throttle+body+gasket

[wheee!]

Deployed on exercise. Not home.

[Zed Head]

Oh.  Be careful with any information you find or get.  I see some bad guesses out there.  ZCD is selling a throttle body that he says will fit both Z and ZX.  But I know that the bolt patterns are different, I've had both.  My memory says that the ZX pattern and opening is smaller.  A ZX TB will not fit a Z intake manifold and vice-versa.

Surprised that he doesn't know this.

https://zcardepot.com/products/big-throat-borla-throttle-body-60mm-280z-280zx?_pos=8&_sid=7968a8baa&_ss=r

https://zcardepot.com/products/throttle-body-gasket-70mm-large-280z-280zx

 

[Zed Head]

I could be wrong about the Z versus ZX fit.  But I have clear memories of different patterns.  Anyway, here's some old instructions that imply the same TB fits both.  Maybe the holes are slotted.

http://xenonzcar.com/s30/files/Weber 60mm TB.pdf

[wheee!]

I have a few gaskets and intakes at home. I’ll get the micrometer out when I’m back. Just thought someone might have the measurements on hand by chance.

[Captain Obvious]

The stock throttle body mounting bolts are on a 60mm square.

Here's a sketch I whipped up a while back for a throttle body spacer I made. Might have some other interesting measurements on it, but the bottom line for the question at hand is 60mm square:

[wheee!]

Darn… now I need to figure out an adapter for mounting the 65mm square throttle body.

[Zed Head]

Is this for a factory stock head and intake manifold?  Most of the horsepower chasers say that the intake runners and head ports are the significant flow restrictors.  

One of the reasons I remember that the ZX TB bore is smaller is because it was kind of surprising that they modified the L28 extensively for emissions and power and ended up with a smaller TB bore than the N42 based Z engine.  

Call me a buzzkiller...

[wheee!]

I ported my intake to increase runner diameter and intake diameter.

[Zed Head]

I'll go ahead and ask before CO does - is your ported port 70 mm across?  Doesn't look it.  70 mm would be outside the 60 mm centerline of the screw holes.  You'll need an adapter with a neck-down transition.  Kind of defeating the point.

They make a 60 mm big bore.  Looks like it would fit about perfect.

One example.  There's probably used on eBay.

https://zcardepot.com/products/big-throat-borla-throttle-body-60mm-280z-280zx

 

 

[Captain Obvious]

3 hours ago, wheee! said:

Darn… now I need to figure out an adapter for mounting the 65mm square throttle body.

Well there's the obvious solutions... Weld the holes shut and drill new, or make an adapter plate? Adapter plate is a little complicated because of the bolt holes all wanting to be in the same locations. Could weld the plate into position or clock the new throttle body 45 degrees to put the mounting holes in a different location.

Take a look at this thread starting on about page 6. Lot of throttle body stuff in there, although at the very end (26 pages!!) I still don't know how it ever turned out.
https://www.classiczcars.com/forums/topic/64413-just-another-damned-z-car-project-thread/?page=6

@conedodger What did you ever do with your throttle body? How did it all turn out?