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OK, on to the next step!!

Now it is important to be very careful to get the pilot holes (pic 1) for the valve seat/port entrance in the right place, firstly the jig must be set up with a coaxial dial gauge to get the start reference point (pic 2). At this point I check several times that the path I'm looking for is correct! I do this by checking my digital readout (pic 3) which is accurate down to two tenths of one thou.

Now I know the placement is right, I put in pilot holes on the valve guide centre. Then, as in pic 4, I cut a slightly bigger hole using an existing port to gauge a rough depth. As the whole thing is finished by hand a bit later on it just needs to be somewhere close. Getting closer to finished size now, you need to cut a larger, but shallower hole (pic 5) (again using an existing port to gauge a rough depth.)

OK, all of this part so far has the table at valve angle, now it needs to be changed to a much steeper angle so we can break through our new chamber into the existing port area! (pic 6) again being careful to check our intended cut in an already used port. This is done with a cutter smaller than the first as it is only a guide for hand finishing. Now we have broken through into the port area, it can be roughed out to shape with a die grinder as in pic 7.

Next step is to cut the seats and set up the valves. More on that later!

- Brian

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