The RV-6 Rebuild project
Page 3 - The Engine
2020 - I ran across this RV-6 in Albuquerque, NM. It has been
damaged, but was priced about right, so I bought it. Not sure if
it was the right thing to do or not, but now I'm committed. At
first glance, it doesn't look too bad. But then there are all the
things I didn't know that I had to learn before I moved it.
Return to Page 1
Return to Page 2
Go to Page 4
Go to Page 5
The engine is a 160 HP O-320-D1A. The logs have been lost, but
has an estimated 1200 hrs since it was purchased new through Vans.
However, it suffered a prop strike with a metal prop when the
plane was damaged. The prop was damaged beyond repair. The
crank flange dials straight, and has been flown since then, but in my
experience, the crank rarely survives that kind of impact without
damage. I also have a personal preference to become intimate with
the engine before I fly behind it. So, it will get a tear down.
The crank will go off to be magnifluxed and balanced. I'll
spec out the case and don't expect it will need anything more than a
good cleaning. The cylinders will make a trip to my buddy Doug in
New Mexico for rework. They should just need a good honing,
probably new exhaust valve guides, maybe new exhaust valves, and of
course a nice three angle valve grind. The Cam and cam followers
will get a good exam, and if there is any question, will make a trip to
Dallas for overhaul.
July 17, 2020 - OK, today is the day I start on the engine. I
only intended to remove the accessories, but got a bit carried away.
Sorry, but I don't take a lot of photos while I'm working.
My hands get all greasy and oily, so I don't want to handle my
phone and get it all lubed up.
Tim wanted to participate in an engine tear down and
assembly, so stopped by to give me a hand. We made pretty quick
work of it.
Here is the exhaust, pistons, mags, carburator,
starter, alternator and cylinders. The cylinders will be going to
my buddy Doug in Santa Fe for honing and valve work. The
crankshaft and rods will go to Aircraft Engines & Accessories in Dallas for
overhaul, and the crank will get balanced if it checks good on the
prop strike inspection. The rods will also go to Santa Fe to be
balanced end for end along with the wrist pins and new pistons.
Here are all the various parts sorted into the bins for the various
cylinders. Not sure why the vacuum pump ended up on this table,
but it goes with the accessories.
The case is still together, but all that's left is to split it.
I was really hung up for a while trying to get this nut loose. It
is hidden under the cam gear, which is not removable. I have
wrenches I have modified in the past to get to this nut, but couldn't
get this one loose.
I was finally able to get it with a 9/16" cylinder base wrench.
More photos tomorrow after I get the case split and start
cleaning up some stuff.
July 17, 2020 - The cylinders will get a pressure wash, then will be
ready to go to Doug in Santa Fe for valve work, exhaust guides, and a
good honing. But overall, they look really good.
The crank needs to be magnafluxed and the dowel pin replaced since it
has suffered a prop strike. It is showing some light scratching,
but should micropolish out as standard if it is still good. It
will go to Aircraft Engine & Accessories (AEA) for overhaul,
micro-polish, and spin balance. The case halves look really good,
so will get a pressure wash to clean them and will go back together.
This case only has 1200 hours on it, and specs out perfectly, so
will go back together after a good clean up. Next day... I
changed my mind. The case halves will go through overhaul at
DIVCO. As long as I am this far into it and doing a Major Overhaul, I
might as well have them zyglo and acid wash them.
The rods look good, but will also go to AEA for overhaul, then go to Doug for and end for end balancing.
The cam looks good, but the cam followers are showing a bit of wear, so
the cam and followers will go to AEA for overhaul / regrind. The
oil pump gears and housing just above the cam in this photo looks
This picture shows the typical cam follower wear. The ring
is worn into the face of the cam followers is caused by the followers
running off center from the cam (by design) so the edge of the cam
causes the cam followers to rotate a bit with every rotation. The
edge of the cam lobe cuts that groove into the cam follower. On a
closer inspection you would note that this circle is actually a very
small series of steps in the face of the cam follower to form the
circle. Each step is how far the cam follower was rotating with
each pass of the cam lobe. These will go to AEA for regrinding.
The accessory case looks good. It will get a pressure wash, then
lightly lubricated to prevent corrosion, and will be ready to go back on.
July 18, 2020 - It looks like rust in the top of the bores, but what
you are actually seeing is the reflection of the exhaust valve on the
polished cylidner. However, look at the image in the mirror.
Yes, there is a significant amount of rust in thes cylinders.
I consulted with a long time aircraft engine builder and had him
take a look at them. He says it's all surface and should hone out
without any issues. Good news for me. I decided to take the
engine case to DIVCO and have them go through it. It will come
back cleaned and alodyned, as well as knowing it meets new spec.
So, the case halveds will get dropped off at DIVCO in Tulsa
Monday morning, then I'll go on to Dallas to drop off the crank, rods,
cam and cam followers at Aircraft Engine a& Accessory (AEA).
The cylinders and wrist pins will go to my buddy Doug in Santa Fe for
what will probably be new exhaust valves, new exhaust guides, a three
angle valve grind, seats reground, and an aggressive honing with a
carbide cutter hone. Additionally, I will send him the connecting
rods when I get them back from AEA, and the new pistons. Doug
will do an end-for-end balance of the rods and mate them up with wrist
pins balanced with pistons. So, when he is done, all the rotating
mass will be balanced, and all the recipricating mass will be balanced.
That makes for a very smooth engine. Most shops just check
that the rods weigh about the same, but don't check one end against the
other. One end of the rod is rotating and the other end is
recipricating. So they need to be balanced separately if you want
a super smooth engine.
July 24, 2020 - I just got home from a 5 day trip to drop off parts at
various shops around the country. DIVCO in Tulsa now has the
case. I went next door to Aircraft Specialties and bought a bunch
of parts. I went to Dallas and dropped off the crank, cam, cam
followers and connecting rods with AEA, then went to Santa Fe to drop
off the cylinders with my buddy Doug to do the cylinder and valve work.
The reports on everything are good so far. The crank is
good, so will be balanced, nitrided, micro-polished at std/std,
the flange will get cad plated, and AEA will replace the rear dowel pin
and remount the crank gear for me.. Doug popped the valves out of
the cylinders and gave the cyliders an initial honing to see what
showed up. It needs exhaust valves and guides. Nothing
surprising about that. The rocker shafts were passable, but also
showing some wear, so will replace them as well. There's a lot of
evidence that these cylinders have been running pretty hot, so my plan
to replace all the engine baffling and build the new up to my standards
is probably a solid decision. I'm also going to move the oil
cooler to the back of the baffling and will probably install a larger
July 25, 2020 - After driving some 800 miles
yesterday, I was not inspired with any desire to do much of anything
today. We'll call it a driving hangover. I did get some of
the parts out of the parts trays and have them ready to clean and
prep for paint next time I am out to the hangar.
July 27, 2020 - I spent much of today cleaning parts
and painting a few. I'm going to be lazy about this engine and
paint it Lycoming gray with rattle can paint from Aircraft Spruce.
This is an example of why you shouldn't use zip ties
attached to the oil drain tubes. Two of the drain tubes have
really deep gouges in them from having zip ties attached to them.
Had they run much longer with the zip ties on them, they would
have gone through and the engine would have been a real oil leaker.
I didn't take any photos, since it was a mess to clean up and I didn't
want to get my phone dirty, but I found an extraordinary amount of
sludge in the oil sump, and very significant carbon deposits inside
the intake tubes that required a lot of scraping to clean. I've
not seen either situation in an engine like this before. I wish I
knew what oil they were using, but I suspect based on other things I'm
seeing inside the engine that it was Aeroshell.
August 28, 2020 - I've had the engine case back from DIVCO for a couple
of weeks. Still waiting for the crank, cam and cam followers to
come back from AEA in Dallas. I love the alodyned finish on the
case. It seems almost a shame to paint it.
Table full of accessories ready to go back on. Also an aircraft specialties box full of bearings, gaskets, etc.
The accessory case is cleaned and ready to go back on.
I fabricated a 3/8 Aluminum cover for the prop governor hole in
the back of the case. Also the pushrod tubes are cleaned and
painted. All the rest of the parts in the silverware trays are
cleaned and ready to go back in. And yes, I have the
Lycoming Overhaul Manual, Parts Manual, and Torque Specs & Min/Max
Clearances Manual in the binder on the table.
The case bolts are cleaned and laying in the
cleaning pan. The top cup has the cylinder base nuts also all
cleaned and ready to go back on. The cup to the right has the
valve cover screws, the intake nuts and the exhaust nuts also all
cleaned and ready to go back on. The cylinders arrived
late today, so maybe I'll have pictures of unpacking them tomorrow
if the weather doesn't cooperate for my planned trip in the SupberCub
this weekend. (The forecast is for thunderstorms, so I'll
probably be unpacking cylinders)
Auguest 29, 2020 - I unpacked the cylinders today and
gave them a coat of Lycoming gray. Note that I did not paint the
surfaces under the cylinder base nuts. That really messes up the
Pistons ready to go in once I finally get to start assembling the engine.
Now That's a hone job! Yes. It is coarse.
But we (Doug and me) have found that a course hone job breaks in
better and runs longer, so he hones them quite aggressively using a
high surface pressure hone with carbide cutting stones. Doug also
core drilled the guides and removed them without wrecking the cylinder
heads, so it took std guides going back in. The exhaust guides
and valves are new. The rocker shafts were all replaced.
It's got a three angle valve grind, and is
ready to go. Doug didn't mention it to me and I failed to take
any photos to post, but I noted a lot of cleanup work inside the intake
and exhaust ports of the cylinders. That would be kind of normal
for him as he can't stand to see unradiused and sharp edges from
the castings left inside the ports.
I also painted the accessory case. today. The plate in the upper
right is the 3/8" plate I made yesterday to cover the prop governor
drive, which I am leaving out of the engine.
August 30, 2020 - I painted the sump today. This is the last
update until I get the crank, cam, and cam followers back from AEA;
hopefully by late this week.
August 31, 2020 - Spoke with AEA in Dallas today. They said my
engine parts should ship today, meaning I should have the rest of the
parts by the end of the week. Hopefully I can get started
building the engine this weekend or early next week.
September 3, 2020 - Yesterdays rant was removed and it's time for
me to eat some crow. The cam followers were packed in with the
camshaft. There are a lot of photos in tonights update as we got
quite a bit done.
Hmm. I don't see any cam followers in here.
They were well hidden inside the cardboard support the camshaft
is sitting in. The cam and cam followers were overhauled.
That means the cam was cleaned, got a new coat of copper, then
had the lobes reground and the bearing surfaces micropolished.
The cam followers had the faces reground and coated with a black
oxide to help hold oil and promote proper cam break-in.
Nice pretty crankshaft. All told, the crank was
balanced, re-nitrided due to the grinding from balancing, the front
seal surface and flange was cad plated, and the bearing surfaces were
The smooth area is where the crank was ground to
properly balance it. Now this was a 1200hr crank as recieved in
this engine from Lycoming. But the balancing shop still took
quite a bit of meat off the crank to properly balance it.
These were stock rods as received from Lycoming.
Note all the grinding that was done to properly balance them as
well. This is how you build a smooth engine. AEA didn't say
whether they needed to do anything to the rods when they overhauled
them. They did install new wrist pin bushings and magnafluxed
them, then shipped them to Doug for balancing per my request.
For those that wonder about prop loads and auto engines. Here's the size of bearing Lycoming uses to carry the prop loads.
Engine mating surface painted with Hylomar and two silk threads.
The white grease in here is Lubriplate Engine assembly lube.
I use it liberally when assemblling an engine. The black
grease on the cam and cam followers is a special Moly cam break-in grease
with a high zinc content. I always coat the cam lobes and cam
follower face with it when assembling an engine.
I warmed, then stretched the front seal over the prop
flange. It gets pressed into place along with some ultra black
permatex after the case halves have been mated. It's amazing how
much that seal stretches and how brutal it is getting it over the
flange. But I have done it many times on both Continentatl and
Lycoming engines and have never damaged a seal. Just for clarity,
you obviously remove the spring from the seal before you install it,
then hook the spring back together behind the flange and insert it back
into the seal once the seal has been stretched over the flange.
The seal will shrink back down to size as it cools. I put
the seal in a cup of water, then heat it in the microwave until it
boils. Then I let it soak a bit and bring it back to a boil a
couple of times until it is too hot for me to handle bare handed.
Then it is pliable enough to stretch over the flange. I had
to heat this one three times before I was able to get it to stretch
over the flange. Even at that, it takes some tools and some
serious leverage to get it stretched over the flange.
This is a video of us mating the two halves of the engine together.
If all you get is the audio on your web browser, you may need to
save the video to your system, then run it locally.
Engine on the stand now and ready to install rods and cylinders.
Rods are now in and rod bolts torqued.
#1 piston with ring compressor on it. Yes, I use
liberal amounts of assembly lube. I slide the cylinder over the
rings, then this ring compressor splits apart on the back side allowing
me to remove it. The inside of the cylinders are also liberally
lubricated with assembly lube. I'll go through a couple of tubes
of assembly lube putting an engine together.
Cylinders on. Tim and I are torquing the cylinder hold down nuts.
Cylinders now mounted and torqued. You can see
that I am inserting the lifters pushrod tubes and pushrods at this
point as the ones on the right are in and the ones on the left aren't.
the lifters don't have any oil in them, I can compress them down by
hand on the rockers to slip the rocker shafts back in once the lifters
and pushrods are in. Note that the lifters are not dry.
They also are liberally coated with assembly lube as I insert the
pieces. I don't fill them up as that would make assembly of the
valve train quite difficult.
The sump is installed and it got a quick coat of Lycoming gray. I
also installed the intake tubes and the rocker box drain lines.
A little Lycoming gray for the rest of the case. Seems a shame to cover that pretty alodine treatment.
Here is the hold up for now. I am missing the 5/16" bolt that goes in the center of the crank gear (the small gear in
the middle). Without that, I am stuck. The bolt was ordered
this morning and will hopefully be here on Tuesday. Until then, I
do have a few other things to keep me occupied.
The bolt finally arrived Wednesday afternoon. I was leaving town
Thursday morning, so haven't touched it. Won't get to it until
I'm home again on Monday. That "special" bolt sure looks like a
standard AN5-10A to me. I've got several of them in my bolt bin.
They cost 77 cents apiece. This one cost me $12 plus $20
shipping for a total of $32 from Aircraft Specialty.
Return to Page 1
Return to Page 2
Go to Page 4
Go to Page 5
Comments or questions; Email me email@example.com