The RV-6 Rebuild project
Page 3 - The Engine

February 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.  

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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 perfect.

This picture shows the typical cam follower wear.  The ring that 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 cooler.

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 torque!  

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 micropolished.

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.  Since 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.

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