DIY Velocity stack

DIY Velocity stack

The 1600 single port build that I have been working on is using a Mikuni carburetor. These are normally found on Harley Davidsons and are fitted with filter covers. Whilst there's a lot of different bling style jewelry air filter cover available (Harley owners generally seem to be some of the worst for bling) this was no good for the 1600S/P build. What I really wanted was a nice velocity stack to finish things off. 


Whilst velocity stacks were available from EPay, I did not fancy paying the extortionate amount that was being charged for them. Seems that like Porsche, once things have the 'Harley' name associated with them the price automatically becomes twice what it's actually worth.

So after watching the Fabricator video - 'Sheet Metal Intake Manifold Entirely by Hand' I decided to have a go myself. First thing was to locate something suitable for use as a former to help shape the conical shape of the trumpet. Fortunately I was able to find a circular punch which had a tapered end. I the pressed this into a length of tube to create a nice tapered shape using the hydraulic press at work.



The result was a tube with a nice taper in the end. Next up was creating the lip of the funnel. In the Fabricator article he simply used the edge of his bench, I was more fortunate as I had a tin-mans stake that had a very similar radius to what was needed. After a little careful hammering this is what I ended up with...



Fitting it onto the carburetor was not a straightforward exercise as the mounting holes are very close to the opening of the inlet throat. To get over this I cut small slots into the side of the velocity stack so that the mounting bolts would have something to hold onto. I used this method of mounting rather then a flange as it was much simpler to implement.

Here's the finished article all mounted up to the engine...



As you can see the stack really sets off the engine.

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