Friday, December 7, 2018

Engine assembly - the beginnings

I received the sump I shipped to Divco for repair in the past week or two so I decided it was time to start assembling the engine.  I have it covered in plastic with a can of desiccant in the bag to prevent corrosion but I would feel much more comfortable if I knew it were filled with oil.  Once the cylinders are on and all external openings are plugged I can make that happen.

First up was to install the idler gears that set the timing between the crank and the cam.  This turned out to be pretty simple...once I found the marks that help with the alignment.  The Lycoming overhaul manual is definitely written expecting you to have lots of experience with these engines.

Next up is getting the cylinder assembled and installed on the engine block which is almost half done at this point.  I ran into a bit of a snag after installing and torquing all 6 cylinders.  When the accessory case is installed there is about a half inch of gasket that sticks down below where the oil sump mating surface is.  You are supposed to trim this excess off with a razor blade and then install the sump.  During my trimming process I managed to "flip" one of the cut ends into the one small opening that would allow it to fall into the case...the just completely sealed case.  I had to remove one cylinder to get access and in the process of trying to finesse the gasket scrap out I managed to nudge it just enough to where it dropped into another hole that I am really struggling to access.  I've tried lock wire, vacuum, cussing (because that always helps) and nothing has succeeded in making that scrap come out.  I'm not going to split the case so I decided to call it a night and think about it a bit.

Unfortunately for the blog this is a rather messy oily process so I didn't take many pictures.

This is the basic setup for installing the pistons in the cylinders.  The cylinder is sticking out of the plastic bag with the piston, rings, and gaskets sitting beside it.

Its hard to see in this picture but deep down in the barrel of the cylinder is one of the piston rings.  Each ring has to be checked for proper gap at a couple of different positions due to the chocked barrel design of these engines.  If you look at the very top of the ring you can see the gap is pretty small down there but has to be a minimum of .0075".  Fortunately all 12 of the compression rings were perfectly gapped.  The 6 oil scavenging rings all needed to be adjusted which was fun...

And once the gaping is complete, rings installed and cylinder barrel oiled its time to slide the piston pin into the piston and slip the who assembly into the barrel.  
Here are all 6 cylinders installed and torqued.  Unfortunately I had to remove the bottom one on the right (#2) to try and get access to that scrap of gasket material I was mentioning.

This is the inter-cylinder area.  I took this picture because I want to make a few modifications to the inter-cylinder baffles.