Engine Overhaul: Build Day 2!

Build day 2 continued with where we left off the day before, which was the installation of the newly overhauled cylinders! 

When we originally pulled the cylinders on this engine, we noted the green paint on the cylinders, meaning they were already P10 (0.010 oversize). They were also in pretty bad shape, with plently of pitting and corrosion on their surfaces.

Since these were already P10, these cylinders weren't looking good for overhaul

Thankfully, Joel at Suncoast Aero Engines looked after me, and kindly sent us down 4 new cylinders. We checked these over and actually sent them back to Joel, who overhauled them completely incuding installing new valve guides & new valve seats. These cylinders were within spec, so did not need oversize pistons. 

I had to unfortuantely work, but Jack had previously reamed the valve guides, and lapped and installed both the intake and exhaust valves.

oooh, nice!

Jack had also gapped the piston rings, and installed the pistons in each cylinder. Before putting the conrods on the crankshaft, each rod and piston was weighed, and the pistons were assinged a spot in the engine based on their weight, to try and balance the opposing pistons as closely as possible. 

This shows how Cyl 1 & 2 (opppsing) are within 0.1 grams, and 3 & 4 (opposing) are withing 0.3 grams.

Each piston has 3 rings - and these are arranged so the top and bottom ring gaps align on the bottom of the piston, and the middle of the 3 ring gap is alinged at the top of the engine - the piston is installed with the printed writing facing so it is upward in relation to the engine orientation.

The pins and pistos were weighed and marked with their weights, then assigned a position in the engine to balance as best they could. The piston was put in the cylinder so it's text was facing upward in relation to the cylinder orientation. 

Cylinder Time!

The actual installation of the cylinders was pretty easy - it was a case of carefully walking the piston out of the cylinder so the rings reamained inside the cylinder, but the piston pin could be pushed out (up). Note that we are using Superior piston pins here, which have the piston pin cap as an intergral part of the pin. 

The cylinder was then mated up to the engine, aligned with the conrod, and the piston pin just dropped in like magic. The cylinder was then pushed onto the piston toward the case, making sure not to damage the o'ring on the studs. 

As we installed each cylinder, we removed the temporary through bolts, and replaced them with the real ones. Each cylinder was then torqued to spec for both the large (50 FT-lbs) and small (25 FT-lbs) nuts. The good old cylinder base nut wrenches came out again.   

I wonder how many engines these have built?

A cylinder going on - it was amazing how easy the piston pin slid in when it was aligned. 

Each step of this build filled me with a sense of achievement!

Rocker Shaft Trap

A note on the rocker shafts - on this engine, there are a couple of shafts which are impossible to get in, with all the cylinders in place. Fortuantely we remembered to install these before we put the cylinders on:

The shaft for Cylinder 1 Intake has to be installed before Cylinder 3 is installed.

Similarly, Cylunder 2 exhaust rocker shaft also needs to be isntalled before Cylinder 4 is installed.

Rockers and Dry Tappet Clearance

Next up, the 2 bags of rocker arms were cleaned and installed. They were seperated into Intake and Exhaust, as the rockers are subetly different. We spent a long time checking the part numbers on these - they are not stamped but very lightly engraved (you would think they would have a better system!). You have to be careful, as the intake and exhaust rocker arms are subetly different.

The rocker shafts are simply slid into place by hand, with a single shim installed on each rocker (in the centre). 

I didn't get many photos of this part of the build - i was too busy having fun (and had my hands in a tub of avgas most of the time). 

It was great to have a little help from a good mate, Glen from Freedom Formation, who happened to be in town in the Little Wings B58. I think he preferred cleaning engine parts to having a coffee!

To check the dry tappet clearance, we cleaned up the new hydraulic lifters in avgas. This process consisted of pulling the plunger out of the body, filling it with avgas, then using a small bit of lockwire in the bottom, to lift the little ball off the seat and 'deflate' the plunger. We did this 5-6 times to clean it out. We then emptied it of avgas, and checked the plunger would 'bounce' on the air trapped inside - this checks the tolerances are good and the lifter will not fail to hold pressure. Finally, the little springed plunger is pushed in until the spring clicks. 

This video shows how it is done:

This is now known as a 'dry' or 'defalted' plunger - and is essential for the next step where we install the pushrods, and check the 'dry tappet clearance'. This was done by roating the whole engine until the cylinder was at top dead centre. A pushrod was installed and a specual gauge is used to check the distance between the rocker face, and the 'rotator cap' on the top of the spring. It needs to fit the small end in (which is 0.028") but not fit the large end in (which is 0.080"). 

A few of the pushrods needed exchanging with ones of different lengths - thankfully the shop has plenty of them! 

The last step was to install the rocker shaft covers, with a gasket and hylomar. 

We are getting Exhausted

This was basically the engine built - but there were a few other little jobs to get done, including installing the exhaust. This was from Clint and Vetterman and is a work of art! When i ordered the fuselage kit, i ordered the kit for the IO390-EXP-119 variant, which has a cowl setup for 2 single pipes (4 into 2) - i had always thought this was the engine i would go for. 

However, since plans changed, i ended up with an Angle Valve IO-360-C1E6 for the engine (originally with an aft induction sump). The sump and intake tubes from IO-360-A1B6 (forward indiction sump), and a cowl for the EXP-119 engine! I emailed Clint and he said he would try and combine all his jigs, and work something out. 

I was nervous to say the least, but the exhaust went on perfectly - the pipes needed to be 460mm apart when installed. A great job well done by an expert! 

An amzing job!

Intake Tubes

Some other little jobs included installing the intake tubes, with their NSFW cock o-rings.

Rocker Covers

We also installed the rocker covers, along with the 'real gaskets' silicone gaskets. These get a very low torque applied. You gently torque them to 25 in-lbs, then once the engine is run, re-check them to 20 in-lbs. I didn't like the original straight slot lycoming rocker cover screws (the ones with the integral toothed washer and the HEFTY price tag), so went with 316 stainless 1/4-20 cap head screws, plain washer and split washer. 

The screws get tightened in a specific order according to Lycoming Service Instruction 1588

A side note on the rocker rovers. The original rocker covers had been chrome plated, and it was peeling off in a lot of places (inlcluding on the insides!). When i enquired about having the chrome removed, they said they needed to acid etch it off - and they could not guarantee the covers would not be damaged / pitted (especially the text). When i spoke to Joel at Suncoast Aero, he kindly sent me a set of very nice CAD plated rocker covers to replace the old ones.  I scrubbed the CAD plating off the front and painted them blue to match the engine. Unfortunately, I did not mask off the little circles under the screw heads, and have noted that the paint is already coming off around the screws. These will need to be repainted again (masking the screws), or perhaps i will get them chromed. A problem for after we get the engine home. 

Oil Drainback Tubes

All new oil drainback tubes were ordered (APS brand) and installed. It's amazing how well these fit. I did not use the normal hose clamps (the ones with the holes in the band) - these cause the rubber to extrude out the holes over time (IMHO). I replaced them with some 16-18mm constant pressure stainless clamps designed to be used on EFI fuel hoses. 

Dipstick / Tube

The dipstick tube was installed - this is not the original plastic tube, but a replacement aluminium tube from Superior (SL75767). I liked this a lot better than the crappy Lycoming plastic one. It was installed using a real-gasket (RG-72059) at the base (and the normal lycoming gasket at the top). We had previoulsly checked the length of the dipstick, as this dipstick was the original one designed for a different sump (i just ground off the old markings). If i need to replace this later, it's just a bit of aluminium rod, held to the cap with a roll-pin and some sealant. 

You can also see the nice contstant tension hose clamps here on the oil drainback tubes.

Oil Pressure Regualtor 

The pressure regulator was installed. This was re-used from the old engine, but with a new spring and ball. 

A couple of paint touch-ups are required.

That's it! 

So that is basically it for the engine build! 

The sense of achievement here is next level - i literally have dreams about pushing the start button on this thing! 

Looking forward to the engine run

There are obviosuly a few more other jobs needed before we can run the engine:

- Install the baffles (as the fuel block mounts on the baffle), and the intake snorkle needs the baffles to attach to. 

- Install the SDS fuel system, which includes the fuel injectors and a fuel distribution block on the firewall (and fuel lines), as well as the wiring for this. 

- Install the SDS ignition system - including installing the spark plugs, mounting the coils, and fabricating and isntalling the igntion leads. 

- Install the throttle body

- Install the SDS wiring - including the Crank Sensor, it's bracket and baffle pass through. Igntion wires and aft baffle conenctor, and sensors such as MAP, Air Temp, CHT etc. 

- Drill the engine mount to some steel tubes, then drill and bolt these tubes to the stand on the engine truck. 

- Install the engine mount to the engine, and mount to the truck. 

I will work on these it the coming weeks, and they will be recorded in the SDS Section of this log. 

A final note

If anyone is baulking at the prices of buying a new Lycoming engine, i *HIGHLY RECOMMEND* buying a core and overhauling it yourself, with the guidance of a professional shop. This experience has been amazing for me - i have literally had my hands on every square inch of this engine, and as a pilot, finally (mostly) understand how these things work and what everything does. It's shameful how little i knew about engines before this. I wanted to build this aeroplane for my own education - and building an engine is the ultimate learning experience! 

It is also a lot cheaper! I will go into the costs of this project, as well as choices we made in the replacementment parts in a future post(s).