So continuing with the body. The inlet and outlet holes were drilled and tapped M5x0.5 and 2mm fixing holes were drilled in the end covers. These were then spotted through to the body and tapped M2. 1.2mm drain holes were drilled in each end cover to release any fuel that leaks past the metering system.
The control end cover required some thought. For the initial tests a simple screw adjuster is required but this must be convertible to a quick acting lever for engine trials. It is also important that the hole in the end cover is less than 2mm diameter to minimise the chance of the adjuster coming loose and the metering shuttle shooting out followed by a jet of fuel at 7 bar. I finally decided to press in a 4mm diameter bronze bush with a 1.5mm hole for the adjusting pin and an M3 thread for adjusting. Even if it becomes unscrewed the shuttle will only reach a maximum stroke of 2.5mm. For the final design I can press the bush back out and replace it with something else.
The drive end is drilled and reamed 6mm for a 4 mm bore bronze bush. Unfortunately the cover pulled out of the spring collet as the drill broke through. I was able to finish this off in the 4 jaw SC chuck as the concentricity requirement are not great.
For the next version I will develop an alternative machining sequence for the covers.
Man o live look at you go! This will be awesome when you get it all straightened out! Really enjoying the build
