KIWI Mk2
I/C ENGINE BUILD
Part 24 By Vince Cutajar
KIWI Mk2
I/C ENGINE BUILD
Part 24 By Vince Cutajar
What was previously used as a mandrel was parted off and finished as the throttle body. A shallow slot was milled to accommodate the handle. This is not in the plans but I thought I would do it to give more support to the handle.
Next the drilling operation of the carb bore had to be done but before that a big decision had to be taken. Westbury states that if should be a maximum of 0.25" (6.35mm) diameter but then he says that for moderate speed and maximum flexibility in control, the bore can be reduced to 3/16" (4.76mm).
So I decided to do the bore 5mm. With the throttle body fixed in place, drilled and reamed for 5mm but did not go all the way to the chucking stub. I did not want to decrease the strength of the stub for the next machining operation. Using the previously made taper D-bit the venturi of the carb was machined . As can be seen in the photo a piece of the D-bit chipped off. I guess it was too hard. Also a sizable burr was produced on the casting. This was cleaned up and then the rest of the 5mm bore was drilled and reamed.