This is an engine ‘mod’ I did last month but never documented.

Have a look at the where the engine builders put the fuel rail to the injectors. They were fitted well and a nice straight line. See the problem?

It is almost impossible to get a tool on the spark plugs to get them out without moving the injectors each time. I see this as a maintenance trap. Yes I’ve made plenty on this build, things that are hard to get to. I have been very conscious from the beginning to avoid that but it is a small plane and as time has gone on I have added nutplates and made more things removable where I could.

It turned out that the injectors have an NPT fitting with the last threads ground smooth where they sit in the injectors. After a lot of thought and fiddling and trying various fittings that were wrong, it turned out they do make an NPT with two AN-6 hose fittings in a tee. That’s the blue one in the picture.

Having dry fitted my new hoses I found that my long cross hose between the two cylinder blocks was .5″ too short. I’d already made that hose several times and refitted it more times. Too bad. I bought more hose and as usual made them up and pressure tested to 1000psi. I’ve also acquired a nice set of aluminium spanners. I should have had these from the start!

Here we are all installed. Note the loops clearing the spark plug holes. I’ve added fire-sleeve with shrink wrap on the ends. There were also many hours getting that breather hose in this final position as well as other items on the top of the engine.

You can see here, the spark plug socket tool is well clear of the injectors as it is for the other three locations. Here I was still testing for clearance before getting that cross hose sorted out.

This is another view of the engine top with items finally tucked away.