Installing Exhaust Manifolds

A tip learned from Jake Raby's Type 4 engine rebuild video is to make sure the mounting surfaces of the exhaust headers are flat and planer with each other. This will ensure they mate up nicely with the heads and minimize exhaust leaks due to gaps. By using a large file I can make sure I contact both pipes at once:

Filing exhaust headers for Porsche 914 engine


With long, even strokes, I work the contact surfaces down until I expose "shiny" all around. Here you can see I need to go a little further to get the 4-5 o'clock area:

Closeup of filing exhaust manifold on Porsche 914 engine


Once I got the two pipes "on the same plane", I put layout dye onto the mating surface:

layout dye on Porsche 914 exhaust manifold


Now, by filing cross-wise (perpendicular to the previous direction) I could look for high/low spots, as can be seen here:

filing layout dye off Porsche 914 exhaust manifolds


Once everything was completely flat, and after annealing my copper exhaust port gaskets (heat them up to a dull red with the oxyacetylene torch), I was ready to install them

The lock nuts that originally held my exhaust manifolds on were a motley assortment. However, I noticed that a few of them were M8 threads (normal) but were only 12mm across the flats, as opposed to the more normal 13mm across the flats. This allows for enough room to get a socket onto the nuts, since they're very close to the pipes. I was surprised to find these odd nuts at my local NAPA for just 45¢ each:

Closeup of exhaust manifold nuts on Porsche 914

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All pictures and text copyright 2008