Brian Meyette's BUILDING THE SUPERIOR SL-360 ENGINE (text only)

This page is based on pictures and notes I took at a "Superior SL-360 Engine Kit Buildup" seminar at the 2003 Oshkosh AirVenture. The seminar was presented by Bill Peterson of Superior Air Parts and Bob Honig of Eagle Engines.

The following is a quick overview of Superior and Eagle. See their web sites (linked above) for more exact details on their products and services.

Superior is a company that makes certificated replacement Lycoming engine parts, and they also make non-certificated complete engines for experimental planes. Their engine is a 180 HP exact duplicate of the Lycoming 360 cubic inch engines, with Superior's added features. They make 2 versions of the 360; an SL and an XP. The SL-360 can be bought as a build-it-yourself-at-home kit. The XP-360 is assembled by Superior. They also have programs where you can go to Texas and supervise them building your XP-360 ($500), or they can supervise you building your own XP-360 at their plant ($1000). Superior is located in Coppell, Texas, near Dallas/Fort Worth. You save about $500-700 by building your own SL-360 at home. You have to pay them $1000 to go to their place to build your own XP-360, so personally I don't know why anyone would want to do that. Maybe they start with a lower "unassembled" price; check with Superior. If you build your own SL-360, it has a 1 year warranty on parts only. At the class, they said the XP-360 has a 3 year warranty, but their web site says it's one year, with an optional 3 year warranty at extra charge. Also, their web site says the warranty starts the day the engine is shipped. I'm not real clear on just what (if any) difference there is (in parts) between an SL-360 engine and an XP-360 engine. Check with Superior. The SL-360 doesn't come with any assembly instruction manual, although they said they are considering making an assembly video (GREAT idea!). You can also get the XP-360 with an optional composite sump that saves 8 pounds and costs $1,000.

Eagle is a partner with Superior. They are located in Redding, CA, and they sell the same SL-360 and XP-360 engines and parts at the same prices as Superior. So, you would buy from whichever source is closer to you. Eagle also makes a custom-built version of the 360 they call the Xtreem-360. They add cylinder flow matching, 3-angle valve job, and Parkerized internal gear train. They also offer custom engine paint and various ignition options. The Xtreem-360 engines have a 2 year warranty on parts & labor. Bob said in class that his warranty starts the day the engine is started in the plane. He also said he balances his reciprocating parts to within 0.2 grams, while the Superior XP-360 parts are balanced to within 2 grams. I don't know what, if any, balancing is done on the SL-360 parts. The crank is nitrided and micropolished, but not shot-peened. The rods aren't shot-peened. Bob says titanium rods are not used in the aircraft industry. Angle-valve cylinders are not currently available, but Bob says they will be available early January, 2004.

Check with Superior and Eagle for all the details and fine print on all the options I've mentioned above.

For the class, we were watching Lou Pierard, Eagle's shop chief, assemble a customer's Xtreem-360 with 10:1 pistons (the max they recommend is 9.5:1, but they'll build it any way you want it), estimated at 220-225 HP. Bob said the 10:1 will wear the cylinders faster, but the customer was willing to accept a 1 year warranty to get the 10:1 he wanted. This is also another reason I suspect they don't offer angle valve cylinders; if this customer was willing to go to 10:1 pistons for max HP, surely he would have also gone for angle valves.

Here is how you put a Lycoming or Superior 360 engine together. Keep in mind that the micrometer work was already done before coming to OSH, so clearances were already set up & measured. The cylinders were fully assembled. All the studs were installed. I don't know how much, if any, of that work is done for you if you buy an SL-360 to assemble yourself; I suspect none of it is done. To build one of these engines, you need to have the part number 602947 Lycoming Overhaul Manual and the #1037 Table Limits manual.

I will apologize once in advance for any blurry pictures. With an automatic digital camera, sometimes it just doesn't get the focus right. I tried to make the pictures large enough to have good detail, and small enough so loading time is reasonable. If you need an original, uncropped, unresized version of a picture for more detail, let me know.

Before beginning, you should use a thread-chaser on all the stud threads. If you haven't used a thread-chaser, it's like a thread-cutting die, except it's made for just cleaning up existing threads.

Wash (with denatured alcohol), dry, and use Permatex #2 on the galley plugs. Install the plugs.

Snap the main and rod bearings into place. You need to mike the crank and bearings to make sure you have the right clearances. They do NOT recommend Plasti-Gage. The engine Lou put together for us had all that already done back at the shop.

Put Permatex Form-A-Gasket onto the left case half, and let it get tacky for about an hour. Look closely at the pictures below to see where it goes - just on the mating surfaces.

Lay the case half onto a wooden stand. A couple cheap bolts in the end of the case will help the case half lay flat.

Oil the rod bolts with plain oil, and apply the rod bolt nuts. The nuts go on with what may look like an integral washer facing OUT.

Lay silk thread onto the left case half, in the middle of the Form-A-Gasket you applied earlier. Let the ends hang out over the end of the case. The silk thread is your gasket. You can use ordinary sewing thread, but make sure it's silk. Be sure you get it around the 4 through-stud holes as shown in the picture.

AUGUST, 2004 UPDATE: I received the following email, so I am putting the info here for your education. I don't know either way; I was just taking pics and notes at a seminar by an engine builder who specializes in building these engines:

I noticed in the pictures it shows putting silk thread around the crankcase thru bolts. I wanted to let you know that I learned this is a NO, NO.

Here is a link to one article about this practice and about failures that have occurred because of this practice

I also have an email from Evan Yearsley, Engine Production Manager, Superior Air Parts, Inc, that I will forward you if you are interested. He recommends against this practice.

Just wanted you to know what I had learned and pass it on to you in consideration of your safety.

Thanks again for your web page. It is really a good review of building the Lycoming.

Here is a forward of the email from Evan. I belong to a Yahoo Lycoming Engine Discussion Group. It was to the group that this email was sent in response to my query.

A fellow from Mattituck participates on the group and he is very knowledgable and informative. His name is Mahlon. I will also forward his response.

Ned, Lycoming Service Instruction 1125B deals with this. It allows the use of 515 or silk thread. If it were me, I would use silk thread. We haven't seen a lot of success with anyone using just 515. The Lycoming factory, at one time, was using the 515 method and stopped. To the best of my knowledge, they stopped due to lack of success as well. Maybe some of the others, in the group, have a different experience using the 515 method and will relate it. According to Lycoming, you should never put sealant or thread between the bearing bosses on the case and I would respect that position and definitely agree with it. As Bill from Superior suggested, the fit of the thru bolts is what is supposed to seal the area, on a body fit thru bolt case. This fit is also what is supposed to prevent crankcase fretting, at those surfaces, by helping to provide some of the rigidity that is necessary at the bearing bore to keep them stationary, while the engine is running. In my opinion putting anything in between the bearing bores may cause a lack of rigidity and help allow fretting which could eventually cause excessive oil leaks, bearing bore dimensional change and possible bearing shift. Good Luck, Mahlon

Ned, I concur with Mahlon regarding his sealant comments. I have no experience with Loctite 515, but have used RTV 102 since it was first recognized and approved by Lycoming. Properly applied, RTV 102 is an excellent sealant. I use one strand of "00" silk thread as "insurance" even though it is not necessary according to Lycoming. I do not apply any sealant or thread to the main bearing saddle surfaces. The RTV must be applied as stated by Lycoming to only one case half and the application must be thin and translucent, being careful to wipe the inside edge and keep the sealant away from the cam journals as pictured in Lycoming Instruction 1125B. Also, just prior to applying any sealant be sure to clean the mating surfaces with a "fast dry" solvent such as Acetone or MEK. When using RTV, one must assemble the parts quickly and snug the attach hardware before the RTV sets up or dries. Evan Yearsley Engine Production Manager Superior Air Parts, Inc.

Lay forward main bearing into place in its locating dowels. Make locating marks on the bearing and case. This will make assembly later much easier.

Put 50/50 mix onto the forward crank main bearing and journal and put both bearing halves over the crank journal. I don't know why they didn't just snap this bearing into place in the case and lay the crank into it, like they did with the other main bearings, but I didn't think then to ask, and this is how they did it.

Use Pliobond on the outer end of the oil seal. Make sure the seal is clean and dry before doing this.

Put the forward main bearings onto the crank, and very carefully, with a helper, lower the crank into place on the case half.

Be very careful to get the main bearing fully seated into its locating dowels (remember those marks you made?) and make sure the oil seal is sitting properly in its place in the case.

Put moly cam lobe lube onto the cam lobes and the lifter bases, and lay the cam into place.

This is a good picture that shows a lot of the details, so I made it big. You can see clearly where the Permatex goes and doesn't go. You can see where and how the thread goes. You can see the rod bolt nut orientation. You can see the crank in place, and you can see the cam in place. You can see the locating marks for the big forward main bearing. You can see the pieces of rubber sheet used to hold the rods vertical for placing the other case half.

Put Loctite 515 onto the right case half's outer mating surfaces. Don't get it anywhere else.

Put pieces of rubber between the rods and the crank, so the rods will stand up straight by themselves.

Double-check everything very carefully before closing up the cases. Use a second set of eyes.

Put Loctite 515 onto the centers of the 4 through-studs and tap them into place.

With a new case, the thru-studs may be rather tight, and may require using a brass drift. Drive them in at least until a few threads are visible on the other side. Put lint-free rags over the cylinder holes before doing this, so you don't knock any crud or brass chips down into the cases.

Note that the perimeter bolt nuts inside the sump area are castle nuts. These must be safetied before installing the sump.

Make a Sharpie pen mark on the case by the case perimeter bolt near the cam gear, to remind you to make sure this nut gets installed, torqued, and safetied.

Oil the through-stud threads, and put a cheap temporary flat washer and nut onto the bottom side. Tighten up the nuts to pull the through-studs through the case, until they are close to even.

Put several washers and a nut onto the top of each through-stud. Use them to snug up the through-studs.

Tighten them to 30 ft-lb. Start with the mains in the center, then do the perimeter bolts. See the overhaul manual for the proper sequence.

Once you pull the thru-studs through enough, install the spacers and the proper nuts.

Pull the piston PART-way out of the cylinder. Do this carefully, making sure you don't pull it out so far that the rings come out. If you slip and the rings do come out, be sure to take your time and very carefully put them back in, using a proper ring compressor.

Pull the piston pin part-way out of the piston and lube it with the 50/50 mix. If you haven't worked on aircraft engines, and you've only worked on auto and motorcycle engines, you might be as surprised as I was to find that aircraft engines don't use piston pin retaining clips. They use aluminum caps that go on the end of the piston pin, and the caps ride on the cylinder walls.

Put the cylinder (with the piston protruding from the base) over the rod and push the piston pin through the rod.

Carefully push the cylinder into place on the case, over the studs and locating pins, until the cylinder base is against the case.

Use a special curved box-end wrench to get at the cylinder stud nuts. This one is 1/2" square drive on one end.

Put on the smaller cylinder base nuts and torque all the cylinder stud nuts to 30 ft-lb.

If torqueing a nut and it causes the through-stud to squeek, or not pull through smoothly (as happened here), or if you encounter any other problems or anomalies in the building, do not just continue. Stop, take it apart, and find the source of the problem.

Be careful the wrench does not slip off the nut when torqueing. The outside of the box end of the wrench may need to be ground down a bit for clearance.

Line up the safety wire holes in the 3 perimeter bolts with castle nuts in the sump area, and safety the nuts.

Also, safety the nut on the through bolt behind the cam drive gear. Personally, I think cotter pins are far quicker and easier and, IMHO, more reliable than safety wire in this sort of application. But we did it with safety wire here.

Put safety wire on the rod that holds them, and use the safety wire to pull the rod tight through the clamping bar.

Install the pushrod cover tubes. Be sure to lube the tube o-rings with silicone to help them slip into place.

Install and safety the posts for the idler gears. Make sure the stud holding one of the idler gear posts is not too high. It must be high enough to get the safety wire or cotter pin through it, but no higher than necessary.

Lube idler gear posts with moly engine assembly grease, and put on the idler gears. Make sure the timing marks line up on the idler gears. This is important.

Install tach drive shaft and its retaining clip with circlip. The circlip holds the tach shaft spacer under it.. Install the circlip with the flat side out.

Lube the pushrods, rocker arms, rocker arm shafts, and rocker arm shaft bushings with 50/50 mix.

Put a screwdriver (gently-!) into the #1 cylinder spark plug hole, and rotate the engine until the piston is at Top Dead Center (TDC) of the compression stroke (both rocker arms loose on valve stems).

Make sure a 0.030 feeler gage will go between the rocker arm and the valve stem. Make sure a 0.075 feeler gage will NOT go between the rocker arm and the valve stem. The hydraulic lifter will handle this range of adjustment. If you don't get the go/no-go clearances described here, get longer/shorter pushrods until you do.

Put a small dab of silicone sealer at the 2 ends and center of the accessory cover mating surfaces on the cases.

Make sure everything is OK under the accessory cover area before installing it. Use a second set of eyes.

Put the accessory cover in place, making sure the fuel pump drive shaft lines up with its driving cam.

Install the valve covers and gaskets. Tighten valve cover bolts until the gasket just starts to squeeze out; no more.

Install the sump, making one last check that the perimeter nuts under the sump cover are safetied.

Put teflon pipe paste (never use teflon tape) onto the cylinder drain plug threads, and install the plugs snugly.

Install the intake hoses and hose clamps. Use as small a clamp as possible, so you don't have annoying tails coming off the clamps.

Install the intake pipes between the intake hoses and the intake ports on the cylinder. Make sure the pipe flange sits properly into the port. Wiggle the pipe to ensure it is seated well.

Torque the intake port clamp bolts to 110 in-lb. You will need a thin wall swivel socket to do this.

Lightly oil the cylinder drain AN fittings, and install the aluminum drain tubing.

The 4 cylinder drain tubes are not all alike; be sure you put the right one in the right place.

Make sure the cylinder drain tubing fit is not forced, then tighten the AN nuts. You may need to bend the tubing slightly or turn the AN fittings a bit to get a good non-forced fit.

Put teflon paste onto the threads of the oil pressure sending unit, and screw that in.