Well, would this do the trick ?
This set will be waiting for you at the next race we both attend. (Bring along your manifold.)
Designed and fabricated by “Felix’s Fixit Facility” for finicky First Flaggers; Patent Pending !
( Pedal’s to the floor hear the dual quads drink / And now the four-thirteen’s lead is startin’ to shrink / He’s hot with ram induction but it’s understood / I got a fuel injected engine sittin’ under my hood ! )
Seeing as you’ve been too busy drilling fancy holes into Alu square pipe, I figured I might as well make a set for you. I was going to do it earlier but I didn’t know the sizing. I finally bought a manifold part from Art so I could work on the pipes.
Should fit nicely on your car!
( For members who may be interested in the technique, I flared the top using the method suggested in my original reply post, #10982 , March 9, 2019, above. But I re-discovered that there was a lot more to it! )
My measurements of D’Arts Dual Four intake manifold: The top face of the carburetors is 4.7 x 5.3 mm, but notched in at the corners. The rings on the top face of the carburetor have an inner diameter of ~2.95 mm, and outer diameter of 3.85 mm. The c – c spacing of the carburetors is 5.85 mm. (Therefore, max flare diameter at top of the pipe is 5.85 mm.)
[ By the way, the Detail Master stacks discussed earlier in the thread will not fit on this manifold. With the 6.5 mm base diameter, they will sit over the edge of the whole carburetor (and will fall over it, since the top face of the carburetors is only 4.7 x 5.3 mm.), and with the flared top diameter being proportionately larger, it makes it impossible to fit the tops within this carburetor spacing. ]
I hadn’t made any of these for many years, and none with this flare profile, so I was looking forward to the challenge with a bit of interest and enthusiasm. However, my method proved to be a lot more difficult than I remembered it; all sorts of strange rings, ridges, bulges and other deformities arising. If anyone is thinking about trying this, Don’t ! ; unless you are prepared to exercise almost infinite patience! This was supposed to be a quick fabrication; many sessions later, it didn’t quite turn out that way! I had to conclude that ‘ There is a fine line between enthusiasm and insanity! ’.
I wanted to get close to the trumpet proportions in the photo of the modified Lotus-30, shown (top of thread). I tried a few different sizes and flare proportions in my attempts, and settled on using 3/16 ” (4.76 mm OD) K&S Aluminum pipe, fitting loosely around the outside edge of the ring on top of the carburetor. The larger base diameter, shorter pipe, and more pronounced flare are all needed in order to approximate the pipe proportions in the photo. I had to throw out my first few attempts at the wide flare; pipes splitting at the top. After a few more sessions, I eventually got smooth surface curves and good proportions. However, with this sizing, and with the spacing of the carburetors on the manifold, there isn’t much room for a large flare. The best that can be achieved in the balance, is the trumpets presented.
( The K&S aluminum pipes seem to all have the same wall thickness, not proportional to the diameter. So, when you go to a double diameter pipe, in order to get the same proportional shape, you have to flair the end at least twice the stretch used in the half diameter pipe, and you quickly hit the malleability limit, causing the stretched edge to split. )
Final dimensions of the pipes made to represent the “ Holley Velocity Stacks ” : Base OD = 5.00 mm ; Flare OD = 7.05 mm (requires pipes to be offset by 1 mm) ; Height = 6.08 mm .
I am including four circle press-cut screens for optional use. One small diameter pair for the bottom of the pipes, one larger diameter for near the top of the pipes. You can use one set or the other, or both, or neither, depending on what you think looks best. The screens at the bottom should be glued in place on top of the carburetor ring, immediately before the pipes are glued in (which should be done while the glue on the bottom screens is still malleable).
The centre to centre separation of the carburetors on the manifold is 6 mm, and the top flare is 7 mm in diameter, so it’s just past the limit, but there is a bit of play in how the bases sit on the carburetors. To get a good fit, the pipes should be placed a bit away from centre and need to be rotated until a good level placement match is achieved between the pipes and manifold. (The manifold sample I am working with has a slight inward tilt on the carburetors; may be just from the flex of the mold or from the original model itself. Some tiny rotating adjustments of the pipes helps.) One way to glue the pipes in place would be to apply a thin ring of ‘shoe goo’ along the inside edge of the bottom of the pipe, then set the pipe carefully around the ring atop the carburetor.
(So Ken, bring along your manifold or whole car, to the next race we both attend. I’ll give you the two trumpets and four screens, and show you the installation details.)
Just consider it my tiny contribution to the cause! Felix