To reduce stress in the heads, the intake
pipes were re-machined to get a thinner wall at the weld area.
This was done on a CNC lathe, the next step however was done
with an old-fashioned hacksaw. First we made a rough cutout,
then step by step we marked the intake pipe, cut off some more,
test fit again, mark off again etcetera untill the pipe had
a nice fit on the head. With a small grinder Aad removed the
cooling ribs in the area where the weld will be, and then smoothed
the intake channel in the head and rounded off the cooling ribs.
Next step: welding!