18. After marking the interferences...
18. After marking the interferences Carlyle removes the pipes and sands them. Note that he uses every part of the belt, like around the wheels and over the edges of the belt (as seen here).
This construction is open to several welding processes. Of course GTAW (TIG) requires the least finishing, which is why Carlyle favors it. But GMAW (MIG) and FCAW (flux-core) will indeed suffice, provided you don’t mind ropy beads or lots of grinding. But there’s an even more appealing option: The flanges withstanding (which work best with GTAW and almost as well with GMAW), this is an application practically made for oxyacetylene welding.
Acetylene welding is appealing because it produces weld beads barely harder than the base metal. That’s good because soft materials move readily. And whether by heat cycling or engine vibration the metal in headers moves quite a bit. The boundary between the soft pipes and relatively hard electric weld beads concentrate stresses that often cause the metal to crack adjacent to the weld. Gas can produce beautiful, small welds but it just takes more practice.
19. Making the entire tube...
19. Making the entire tube fit the cone perfectly isn’t ideal because the angle between the primary and the cone is less than 90 degrees. Instead, Carlyle fits the “heel” perfectly and lets the “toe” run long and curl away from the cone (as seen here).
We’ll also expand upon another piece of advice in the captions but here it is in a nutshell: start with the side that has the rearmost-offset cylinder bank. One bank of a V-configured engine sits slightly behind the other. With a few exceptions (big Olds, Poncho, and the late OHV Caddy for examples), this means the passenger side, and on some engines, the offset is huge (roughly 3 inches for big Chevys).
Doing so establishes the forward-most position where the header ends. Start there and you can lengthen the other side’s header to match; however, if you start on the forward-offset side you may not be able to shorten the rearmost offset header to match.
Beyond that, though, the world is your canvas: primary pipe angle and length, cone angle and length, and construction style are open to your interpretation. As Carlyle worked he explained how fit and style largely prevail in lakes header design. Get a grasp of those and a mastery of some simple tools and you’re guaranteed a header that’s unique, just like your car.
20. Carlyle has another mandrel,...
20. Carlyle has another mandrel, this one a heavy-walled pipe about 1 1/2 inches across, welded to a flat bar that he clamps in his vise. With this and a hammer he can flatten the toe of the bend down to better follow the cone.
21. The net effect of this...
21. The net effect of this process reduces the angle of the bend, at least at the toe. Cutting the tube further up has the same net effect of reducing the angle but it also eliminates the gradual taper that makes each tube seem to flow into the cone.
22. Altering the angle also...
22. Altering the angle also unintentionally changes the tube’s diameter at the toe. In this case the diameter decreased, which disrupts the tube’s fit against the cone.
23. Another trip or two to...
23. Another trip or two to the belt sander removes the gaps. Carlyle uses the instincts he’s honed over the years but you’ll probably want to mark the areas to be sanded. At the very least remove the smallest amount of material each time.
24. Move slowly and you’re...
24. Move slowly and you’re almost guaranteed a perfect fit. While gaps can be filled by welding it’s a better idea to make the tubes fit tightly. That assures a stronger, better-looking joint.
25. Just as he did with the...
25. Just as he did with the leading primary tube, Carlyle cuts the remaining primaries to fit between the stubs and the cone.
26. Earlier he tacked the...
26. Earlier he tacked the leading stub and primary to the cone. This time he just tacked the primary to the stub. Instead, he simply marked the fit between the primary pipe and cone.
27. Only after he fits all...
27. Only after he fits all the tubes does Carlyle cut their openings. He simply transfers the shape to the cone and cuts out the appropriate size. He bores the ends with a big drill in a press.
28. Any number of methods...
28. Any number of methods can connect the holes but Carlyle favors a pneumatic nibbler. He does, however, clearance the jaws so the nibbler will cut highly curved surfaces.
29. He then finishes the opening...
29. He then finishes the opening with a sanding barrel. Resist the temptation to make the hole exactly as big as the primary tube. The engine will never notice that slight overlap but you’ll appreciate it come time to weld the joints together.
30. Welding on perfect edges...
30. Welding on perfect edges is tricky, especially when a pipe obscures the exact location of an edge. The slightly smaller openings in the cone act as a bit of a heat sink, which reduces the incident of blow-through. That’s particularly comforting if welding with acetylene.
31. Here’s why Carlyle can’t...
31. Here’s why Carlyle can’t cut the big end of the cone: his flange would be too big. And likely you can’t for the same reason if you use a ready-made flange. In fact, the same holds true if the cone merges into a pipe. Of course all bets are off if you’re dumping the headers into the open.
The final product is not just functional, it’s quite beautiful. And if Kozsis measured right, they’ll fit as if Carlyle built ’em on the car.