Cylinder Partnumber issues..

[Cubswede]

Hi all.
I am doing some "Deep engine maintenance" on a friends experimental PA 18A 150. He is unfortunate enough to have a corroded cam that needs replacement. Engine around 500 hr s.o.h.
We will send the Engine, less cylinders, to a approved Workshop to replace the cam and cam followers.
We were thinking that now is a perfect opportunity to upgrade to 160 HP.. If it only was this easy..
We needed to replace two bad cylinders that was burned beyond repair at the exhaust port. Luckily I had two OK cylinders he could buy very cheap. The cylinders are all LW-12417 and two of them are painted blue on the cooling fins, indicating they should be nitrided, and the other two are plain grey.
Since upgrading to 160 hp, nitrided cylinders seem to be mandatory. My issue is that I cannot figure out if the LW 12417 cylinders are nitrided or not. I found some info in an old lycoming Part manual that they are plain steel cylinders, but still two of them are painted blue..
Today only the nitrided cylinder is used for 150 and 160 hp O 320 with P/N LW12416. I had a look in Lycomings part superceedure document, stating that LW12417 and LW12416 are interchangeable. For me, this means that you could install a LW 12417 cyl on a 160 HP Engine. But then I contacted a Lycoming field techrep about this to verify, and he stated that the approved cylinders are those in the Lycoming SI 1037, I.e LW 12416.
So I am still very confused, not only what is true, but also if we decide to install theese cylinders without upgrading, what Piston rings will I use? The compression rings for nitrided and plain steel cylinders are not the same..

As usual, I Believe that the best answers, and/or solutions comes from this great forum and all you knowledgeable folks

[algonquin]

This is just my opinion so for what it's worth. From what you wrote it seem to me your not sure what you have and they are from different engines. Your playing with fire. If there were two cyl.'s cooked and your going to reuse the other two by just re-ring , again rolling the dice. If it were me I'd just send them to a certified shop and have them do what you want and then you'll get four cyl.'s done right. Remember in a Cub you only have one engine. Good luck.

[Cubswede]

Well, I am sure I have 4 Cylinders with P/N LW 12417 stamped on them. And Two are painted blue on the fins. This could have been a mistake from the previous overhaul, but I want to educate myself to be able to determine technical details myself.
The fact that they are from different Engines is no problem from my Point of wiev. The ones I had came off my own super cub in serviceable condition, with around 900 hr on them due to upgrade to 160HP (I bought new cylinder assembies). My cylinders has a known history. I am only trying to find the most "cost effective" sollution for my customer. I have measured the bore and out of round to verify they are within limits, and all four are more than OK. I was planning on honing all four cyl´s and install new pistons, rings.
The two "cooked" cylinders is damaged because the exhaust gasses has leaked past the exhaust gasket during what I think, a couple of hundred hours. The gasses has eaten away the metal in the exhaust port. The other two is just fine, with only 500 hours on them. This is the first annual for me on this cub, I have found a lot of other issues that has not been taken care of very good by the prevoius "maintainer".
Of course I could send the cylinders to an approved workshop, but then the cost to have them checked will be so high, that a new set of cylinders will be the better choice. In europe, there are not many approved workshops, and certainly not next door to where I live. If i can, I am trying not to go this way. It would be unneccesary to throw away serviceable cylinders.
Anyway, does anyone has knowledge if there is any way to see difference between a Nitrided and a Plain steel barrel? Somewhere I have read that the Nitrided are choked barrels, and the plain steel are straight. If this is true, it will be easy to find out what is what.

[Steve Pierce]

If the exhaust flange is eroded could you use this tool to fix them? http://www.supercub.org/forum/showth...-Exhaust-Issue
I know the standard steel cylinder with 160 hp cylinders will wear the choke out in a few hundred hours. I use the service instruction for piston ring compatability. If I wasn't sure what the barrel coating was I would call Lycoming and ask them how to identify, I am use to doing this by paint. A cylinder shop might help as well.

[algonquin]

This this is the code markingsColor Code for Cylinder Identification[COLOR=rgba(0, 0, 0, 0.87058]

• Location – Between push rods on cylinder head, or band around base of cylinder barrel.
• Engine gray or unpainted – Standard steel cylinder barrels.
• Orange stripe – Chrome-plated cylinder barrels.
• Blue stripe – Nitride-hardened cylinder barrels.

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