Barefootdan's 280z Build

[dar5052]

@Barefootdan that looks great, hopefully mine can look like this when Im finished. I pulled all the interior and wiring this weekend. Its basically ready for the patch work and paint! keep up the good work!

[AZDatsun]

If you ever want to borrow a welder or come over and weld I have one and I am in Gilbert did my floor panels/frame rails and tons of other stuff with it. Just let me know. unfortunately I was too late for the panel bond posts

[Barefootdan]

1 hour ago, AZDatsun said:

If you ever want to borrow a welder or come over and weld I have one and I am in Gilbert did my floor panels/frame rails and tons of other stuff with it. Just let me know. unfortunately I was too late for the panel bond posts

Thank you, I appreciate it! 

[Barefootdan]

Wasn’t expecting to pick up these beauties. But they came up locally for an amazing price and I couldn’t pass them up!! 

 

im not sure yet if they are 40 or 44mm or the intake manifold brand. I’ll be tearing them down for a clean and rebuild which should answer some of my questions. 
 

I can’t wait to get all of the ugly EFI components out of the bay…and one less harness to make! 
 

Time to read up on these bad boys 🙂 

[ETI4K]

They'll sure be pretty once cleaned up.

Nice find!

[Barefootdan]

Took out the old efi setup and manifold. Wow it’s so clean now without all these wires! 

The butterflies has a stamping of 175 which leads to the 44mm version. This should play nice with the high compression pistons and eventually a cam. 
 

I mocked up the new manifold for fit and just to get a sense of everything. I wasn’t able to find any stampings or markings on the manifold, does anyone recognize it by chance? I also noticed the top 4 mounting holes won’t fit the oem style bolt since the runners are so short. I’m assuming I’ll need to switch to a stud and nut setup? 

 

Next tasks to figure out are the mounting studs, linkage setup, choke pull (is this needed in Arizona temps? Sorry this is my first carburetor!) and rebuild kits. I’ll grab a low pressure fuel pump and regulator to get around 3-4psi of fuel and use my return line as well. I might print my own velocity stacks in the mean time since they go for a pretty penny. 

[grannyknot]

You may already know about these guys, there's not much they don't carry.

https://www.piercemanifolds.com/productslist.asp

[Barefootdan]

I spoke with Taka over at Kyusha House, very nice by the way, and we identified the manifold as a Mikuni. Even though there is no stamping, Taka let me know that there are version with and without stamping. I opened up one of the carbs to get a better idea of the inside condition and luckily it was not bad at all. No jets appeared clogged and there was no gunk in the bowl. I think (and hope) an ultra sonic cleaning will suffice. From there I would like to get all of the hardware plated so I will be researching recommended places to send the hardware off to. Also, it is nice that rebuild kits are easy to come by. Even the diaphragms are available which I will replace just in case. The jetting installed looked to be the original jets and choke size, so I will start with these and see how she runs.

 

I will take a break from working on the car during the holidays, so I have been playing with Fusion 360 in my spare time. I came up with a simple velocity stack design, 100mm long. No idea if my initial radius are optimal, but its an easy change. I tried to maximize the diameter of the trumpet without causing interference with its neighbor. The flange was super easy to create! Up next will probably be a throttle cable bracket as I am missing that piece on my first carb. Everything will be printed in ASA, which should have enough heat tolerance for this application. A heat shield under the carbs will also be used. 

 

[Barefootdan]

Quick question I haven’t had much luck researching on…in my last photo of the manifold, there are 3 locations for studs. The center, larger, is what I plan to use, with a smaller hole on either side. What are these for?

[Captain Obvious]

If I'm understanding the question correctly... You're asking about the three holes in the mounting flange of the intake manifold?

All three of those holes are for mounting manifolds of different designs. The intake manifolds used on cars that came with carbs use the two smaller holes that border the larger one in the center. And the cars that came with fuel injection used the one larger hole in the center.

I'm guessing that the people who made that custom intake manifold put all three holes in it so it would bolt up correctly to either an older (carbs) or newer (FI) head.

 

[Barefootdan]

Thank you @Captain Obvious!

[Captain Obvious]

Glad to help. And since that helped, I can add a little more info.

The early heads (up to and including 74) were drilled and tapped for the carb intake manifolds. They did not drill and tap the center hole.

The later heads (75 and up), however, were drilled and tapped for BOTH the carb manifolds AND the fuel injection intake manifolds. Point is... If you're putting that triples manifold onto your original 280 head, your head will have drilled and tapped bolt holes in all three positions.

For mechanical purposes, you won't NEED all three at each end, but if there's enough space between the heads of the bolts, you should put something into all the holes just to keep the critters out.