milks-models

Session 1

The fuel system is via a venturi effect, where the fuel is drawn up from the tank and then into the crankcase. The amount drawn in is controlled by a
needle valve which is tapered, therby increasing the amount as the needle is withdrawn.

Firstly a bar of brass was turned to diameter and length. Then it was drilled through and one end tapped to match the crankcase. Using a button cut
form the end it was taken to the milling machine and cross drilled and threads cut.

The spray bar, which connects to the tank of fuel, was then constructed and with a washer, was then screwed into the main bar. This spray bar had
different diameter drills through it whech made a seat for the needle in the thimble, to seat on. All were fairly straightforward but I must admit it was to
close tolerances, which whilst challenging, was a rewarding experience (thats what I say now..if it doesn't start I may change my mind!)

Using the Myford ML10, due to size of the parts to make, only served to remind me how good a machine it is compared to cheaper imports in regards
to quality. Also, because it doesn't have any DRO's I had to refresh myself in using the graduations marked on the top and cross slide. So at the end of
the first session I had the three main parts made, but not finished.

time taken 3 hours 10 minutes.

Session 2

This session saw the the srpay and main bar soldered together. As always I used too much solder. I did use some masking paste for the first time for
the thimble in particular. It worked very well but it was very difficult to take off. However eventually it did clean up. Once soldered together it was
placed back in the lathe and drilled through again to remove the central piece and allow air through. The needle was tapered at the end as per plan and
then soldered into the top. The article by Ron Chernich described the method to get the needle in the right place. The needle was placed as far in as it
would go with the thimble closed fully. It was then openend up 1 complete turn and the needle checked that it was still sat home. In this position the
solder was applied and made into a blob as per the original engine,

The next task was to make an 8 deg included D cutting tool and cut the tapers in the main bar. once these were done it only required two nuts to be
made. One for the tank to be connected and the second as a lock nut on the connection to the crank case. (see photo's above). This completed the
fuel system and it was screwed to the crankcase before being disassembled, polished and final assembly.

I quite enjoyed this part of the build although I may have to do it again if I find my sizes are suitable as they deviate from the plan. Only when Ron
answers my quries will I know. But I won't be too upset if I have to make another set.

time taken 3 hours 20 minutes total 6 hours 30 mintues (Good job I am not paying an hourly rate, the engine would cost an awful lot!)