Here are some updated pictures of how to be able adjust the tach to read correctly for 8 cylinders.
I soldered a 10K pot from pin 4 to pin 7. With that you can adjust it so the tach reads correctly for an 8 cylinder vs 4 cylinder.
pins-1-through-4-caps-moved
pic1a
front-view
back-view-with-case-on
showing-pin-1-of-the-chip-copy
pins-5-through-8
