MSefi.com read only forum (Jan.15,2018)

The Escort that we get the EDIS modules from (early 90's?) has an aluminum manifold with some nice curved runners which would work well as a basis for building a log manifold from. Would be about the right size diameter for your engine, but would require a bunch of fabricating.
I have been considering this for my car as well (to experiment), but haven't got there yet........
My Datsun has the same intake/exhaust setup as your Spit. I just built a straight runner manifold with a 2.5" plenum. Runners are ~10" long. Little bit longer than the original twin SU setup, but should provide a bit better torque with the long individual runners as compared to the shared runner split just before the head (I think??).

Someone else here, who knows more than I could probably also verify that you will gain more torque (and horsepower) with the efi AND ignition control, than just the extra long intake runners. Especially in the lower rpm range.

I did the EDIS ignition first on my car with the SU's, and the gain in torque at the low end had me spinning the tires on starts until I got used to it.

Yep, it was a photo of that Escort manifold that first turned me on to the idea of using an existing factory manifold. Before that, I was looking at aluminum tubing... aluminum mandrel bends ($$$), etc and thinking about how to put it all together. But a lightbulb came on when I saw that manifold. Even if you're constructing a manifold... there are some cool bits and pieces that could be salvaged from a junkyard manifold!

Hi Loren,
I came to the same conclusion with my landcruiser 2f I6 motor. The later 3f motor came with injection but the manifolds are hard to come by and way over priced if you can find one. I thought about making my own manifold from scratch, then had the idea to see what I might be able to use from some other vehicle.
I ended up using the manifold from a similar displacement ford motor. This manifold is in 3 sections, the plenum, the runners and a flange section with the injector bungs that bolts to the head. The 2f motor has the intake ports configured in pairs and the ford motor is a crossflow design (ports evenly spaced), so I ditched the section with the injector bungs and made up my own adaptor section. By doing this I was able to put the injector bungs close to the intake ports. I made the runner length for this section about 6" long hoping to increase bottom end torque - the 2f is also a low reving engine and it's in a 4wd not a race car.
I have only just finished the intake and still have work on the fuel supply side of things to do so can't say how well it has worked yet.

Dusty

You could always fabricate it out of thin wall mild steel. That works well and isn't as heavy as you may think.

Mild steel is nice to work with. Then you can fit the pieces, tack it together with a cheapo Mig or even a stick welder and then take it to a shop to have it completed if you're not confident in your welding skills. It won't crack if you need to adjust a bend and it isn't overly sensitive to being worked. (Both drawbacks to aluminum.)

-Brian