Stock Intake Manifold Modification

[Steph]

I was lucky enough to recently obtain an intake manifold from Mike, and the plan was to modify the manifold to suit the 32/36 DGV Weber carburetor. As anybody who has seen the adapters knows, they are less than ideal, so my intention was to have extra material (aluminium) added to the back of the carburetor flange so I could open up the manifold to match the Weber. So far, I've had the manifold welded, and now I need to drill and tap the holes for the studs to be fixed into, and then open up, and blend the opening to provide an ideal passage for the atomised fuel and air to flow through. Here's where I'm up to...

This is the manifold in the early stages, before it was cleaned and had all the studs removed...

and from the back...

In this one the extra material has been added, and waaay too much I might add...

Here's what it looks like from above. You can see I've marked out where the new opening will be, plus where the studs need to be re-mounted.

A chemical bath was done to clean it up. I was quite shocked when he brought it out, it looked like new.
...and that's as far as I've got

This is the A/T Engineering manifold and Weber DGV 32/36 carburetor kit they used to sell. My manifold is inspired by their design, right down to the 1" carburetor spacer with correctly sized venturis, rather than a gaping space where the velocity of the air and fuel slow down. The phenolic spacer also acts as an insulator, and I'm going to use 8mm stainless studs that I'll make by removing the heads off some stainless cap-head bolt I have, instead of using the studs supplied, as the stainless won't transfer heat from the manifold to the carburetor. This setup is reported to increase bottom end and mid-range power, which is exactly what I'm after...

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I paid a radiator shop to do the welding (A$100), and it should go without saying that they used a very powerful TIG welder, and apparently they pre-heated the manifold in an oven before welding it. Lots of work and the guy told me he'd never do one again because it took ages longer than he expected,

[Steph]

Finished milling out the manifold today. I used an end mill for most of the work, but finished it up with a die grinder with various shaped bits to blend all the edges. I still have to drill and tap the threads for the studs, which shouldn't take long at all. I've put a 5mm open-mouthed phenolic spacer on to show the fit, and the 22mm phenolic spacer pictured above will go over that for a total of 27mm of extra height, with the added bonus of completely isolating the carburetor from the heated manifold.

Steph

Before

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After

[Steph]

Here's a pretty convincing image against using the adapters that come with the Redline carburetor kits. My intake manifold is an exact fit for the Weber DGV 32/36 and beside it is the adapter plate that came with my kit. I honestly believe that by using the adapter plate you'd be hard pressed to get any advantage over the stock carburetor, as it's quite plain to see that it's chocked down to 50% of it's original size. I also think that this massive restriction plays a large part in the advantages of the sidedraught carburetor in regards to raw power. Now all I have to do is sort out the cornering issue. If it starves for fuel, couldn't the fuel bowl be enlarged? I remember in go-karting this was a standard mod in one of the grades I raced in. The fuel bowls would get milled out to maximum they could get away with, and they would double stack the pump diaphragms. So what part does fuel pressure play in this issue?

Can anybody tell me what size the EB3 intake manifold outlets are? I would expect they would match the 33mm intake ports on the EB3 head?

Thanks,
Steph