12 Oct 2009

Sorry for the late update; yesterday was a long day. Pushed hard to get the entire manifold tacked up and got it done late in the evening; the pictures pretty much sum it up. A header is great fun to make – lots of room for creativity. The primaries are within about 1/4″ of each other, and for a turbo manifold I’m not going to sweat getting closer than that. While not intentional, the manifold somehow looks like it belongs on a drag boat…

The big concern – like always – is heat distortion. The worry is that as it’s finish-welded, the tube assemblies will move round enough to ruin the collector slip-joint alignment; all four tubes have to line up just right or the tubes will jam part-way on. Each tube assembly will be welded separately, polished, then welded to the cylinder head flange, giving one last chance to tweak alignment. Even then, as each tube is welded, the flange will distort (it’s common that header flanges have to be ground flat after final welding. Small misalignments at the flange-end mean big misalignments at the collector.