STUART LIGHTWEIGHT PETROL ENGINE BUILD

Part 12 - conclusion - by Jason Ballamy

The float chamber and vertical pipe are joined by an angled piece of brass which is a bit tricky to machine as it does not run on the same centre line as either of the other parts.

A 1/16" pilot hole was drilled through some 5/16" brass which was then held at the correct angle in an ER32 block, the centre found and the DRO used to give the correct offset for the float chamber and a boring head used to do the cope cut to match the 1.5" float chamber diameter.

To ensure the work did not twist out of line when the other end was cut I used this method to change the grip of the work by tightening the 5C block before loosening the ER block the part stays indexed to the edge of the blocks.
The 5/8" cope cut was then made with a similar sized milling cutter using a few plunge cuts.
Here are all the carb parts prior to soldering, there is also a web cut from 1/8" flat to brace the joint between float/diagonal and vertical parts as well as a small boss for the mixture needle to screw into.
And here they all are soldered together. I passed a bit of studding down through the vertical parts with a nut and washer on top and packing below to hold those parts together, the boss on the bottom of the float chamber sits in another hole and you may just be able to make out a slotted screw holding the needle boss in place - I centre drilled this prior to soldering so it was easy to locate and drill out later. Block of metal at the bottom and the packers were given a good coat of Tipex correction fluid so they did not get soldered, too.
That’s the last construction photo I took but there was some minor machining of the assembled carb and a sight glass for the oil feed added, too.


So, time for a coat of paint in a nice subtle shade.


See Part one here  part two  part three  part foupart five  part six  part seven  part eighpart nine  part 10  part 11  part 12