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mask or pattern for marking irons for porting. The mask must be indexed by the dowel holes. Drilling the hole for the first dowel is easy. Getting the second one accurate is the hard part.
The transfer punch locates the center of the second hole the correct distance from the first dowel, in this case, or from any other feature or hole in another application. For smooth sided holes, the punch is made from stock larger than the hole, and turned down to become a very light press fit into the dowel hole.
The point is drilled so removal from the dowel hole is easy. The hight is adjusted by adding washers to the bottom of the dowel hole.
Once you have one dowel hole drilled and reamed to fit the dowel nicely, install the punch in the opposite hole with about 1/16" of the point extended above the surface of the iron. Now install your mask material (aluminum) with a dowel through the first hole and into the iron. Lay the mask on the iron and align it as you like. Then tap the surface of the material over the punch with a light hammer blow. The punch will mark the mask dead center over the dowel hole.
Once you have the two holes installed and are happy with the accuracy, you ink up the iron side of the mask and scribe the port shape into the mask gently with a sharpened piece of welding wire through the intake runner.
Drill through the port shape on the mask and trim to the lines with a die grinder. Don't go too far. Keep installing the mask on your ported iron to be sure of where you are going with that die grinder.
Stamp the port timing data on the mask.
Lynn E. Hanover
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