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Cracked O-320 Case - Best way to proceed?

Thanks for the good ideas guys. I went to see my IA today, and we agree that the plane is best to be grounded, pending a true fix, rather than a bandaid. Especially since there was metal in the screen for the first time this oil change. I have some phone calls to make, the first being DivCo. I'll report on the path chosen. Thanks again..
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Sure sorry to hear about this Gordon. FWIW (probably not much) if it were me and I had to pull the engine down, I'd do the 8.5/160 conversion without a second thought. I don't think there are any material differences in the case. Once you swap the studs and cylinders, you have a wide deck, to the best of my knowledge. I think the WD cylinders have slightly bigger base fins and you'll have to modify the baffling slightly, but I'd do it without hesitation. My $.02.
 
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Well, DivCo says my case is not repairable due to the location of the crack. So I'm looking at a "new" case for sure. Now the question is whether to stay with 150 HP or upgrade to 160 HP. DivCo has narrow deck low compression and wide deck cases in inventory, and they are the same price. They don't have the high compression narrow deck, and cost to convert would be prohibitive. In the opinion of Lucas, the gentleman I talked with there, neither narrow nor wide is better than the other overall.

160 HP is tempting, but would require different engine STC (Crosswinds?) and different mogas STC (Peterson) I currently have the spotfaced (low compression) narrow deck cylinders with about 480 hours since major overhaul. So conversion would mean get a wide deck case and compatible cylinders. My current cylinders have around 500 hours on them, compressions in the mid to upper 70's at last annual.

Two questions:
What firms would you recommend for exchange cylinders?
What's best - steel, chrome, nickel, or nitride? Why? I typically fly around 100+ hours per year. Humid climate, but hangared.

Thanks!
 
Gordon,

Really sorry DiVco couldn't work a fix I've been in the shop on several occasions over the years and they have amazing talents, many years ago the welded up a 495 KTM Case for me that I quenched when hot and it cracked.

As for the future, I upped my 150 Wide Deck to 160hp several years back and wouldn't go back but I fully understand the cost side as well. I would say if you can swing it do it, and maybe you can pick up a ready to go engine and trade in your serviceable parts.



Kirby
 
Well, DivCo says my case is not repairable due to the location of the crack. So I'm looking at a "new" case for sure. Now the question is whether to stay with 150 HP or upgrade to 160 HP. DivCo has narrow deck low compression and wide deck cases in inventory, and they are the same price. They don't have the high compression narrow deck, and cost to convert would be prohibitive. In the opinion of Lucas, the gentleman I talked with there, neither narrow nor wide is better than the other overall.

160 HP is tempting, but would require different engine STC (Crosswinds?) and different mogas STC (Peterson) I currently have the spotfaced (low compression) narrow deck cylinders with about 480 hours since major overhaul. So conversion would mean get a wide deck case and compatible cylinders. My current cylinders have around 500 hours on them, compressions in the mid to upper 70's at last annual.

Two questions:
What firms would you recommend for exchange cylinders?
What's best - steel, chrome, nickel, or nitride? Why? I typically fly around 100+ hours per year. Humid climate, but hangared.

Thanks!


Call colorado airparts at delta colorado just to see what they have, just an idea.
 
Was talking to Ken Tunnel at LyCon a lititle while ago on another matter. He said he saw more cracking with early and middle production wide deck cases than he ever did on narrow decks. There are a few more.pieces you'd have to change if you convert from wide to narrow.
 
I am not a big fan of rebuilt cylinders, especially ones that you do not know the history of. For a few hundred more just get new ones.
DENNY
 
What's best - steel, chrome, nickel, or nitride? Why? I typically fly around 100+ hours per year. Humid climate, but hangared.

I would think Nickel would be superior in our climate Gordon
 
Was talking to Ken Tunnel at LyCon a lititle while ago on another matter. He said he saw more cracking with early and middle production wide deck cases than he ever did on narrow decks. There are a few more.pieces you'd have to change if you convert from wide to narrow.
Thanks Steve. That's pretty consistent with what DivCo had to say. The two tend to crack in different areas. Though he said the wide decks tend to be repairable, while the narrow decks tend to be less so.

Could you please clue me in on what other pieces would need to be changed?
 
The only thing I remember are the idler shafts that bolt to the back of the case.

I was at Gibson's cylinder shop when the first set of Nickel cylinders started coming in for overhaul after TBO. Marshal told me the barrels still measured new limits. The other advantage is they don't rust. I have installed quite a few and they have been good. I did have a C85 peel the nickel and contaminated the engine. That was after ECI got bought by Continental and it took some threats to get the repairs taken care of since the cylinders were still under warranty but they did finally step up. Just put 4 new ECI/Continental O-320 cylinders on my Dad's Clipper but he wouldn't spend the extra money for the nickel cylinders. His 1700 hr Millineum cyllinders had some corrosion pitting. He use to fly 130-150 hours a year but now it is more like 40-50. I wish he would have installed the nickel because Memphis is pretty humid but he build an engine dehumidifier.
 
Thanks Craig. Could you tell me why please? And thanks again for your advice yesterday - - -

Steve pretty much summed it up. I have been fighting low compression in plain steel cylinders at annuals since i bought the plane and all have been leaking by the rings. I've heard from engine builders (including yours) that the nickel breaks in fast and will not rust. Now I am in the middle of overhauling my 320 narrow deck and upgrading to 160hp which requires different cylinders anyway, the Nickel was an easy choice for me. Your scenario may be a little different having decent lower time cylinders making it harder to justify. If your cylinders didn't need a lot of work maybe ask about plating yours? Just an idea
 
Thanks Steve and Craig. Makes sense re the nickel. It's probably soft in the as-plated condition, then work hardens during break-in.

I'm still very interested in suggestions for good trustworthy source(s) for exchange cylinders. Suggestions??

Thanks - -
 
A common misperception is that the narrow deck case is lighter than a wide deck. I spent time at an engine overhaul facility and weighed about 10 different cases. The lightest case is the mid 1960's wide deck by several pounds. After the late 60's the wide deck cases got progressively heavier. The narrow deck case is heavier than a wide deck up to the early to mid 70's.

Just thought I'd throw that out there

Bill
 
It is my understanding that there is a modification which can be done to the narrow deck cases which installs a bushing or pin which straddles the joint between the two case halves. This helps to prevent the fretting situation which requires the milling of the case haves to correct. I believe that this is one of the things which were done to increase the TBO from 1200 to 2000 hours. Yes changing the valve diameters was also one of the changes.
 
Alignment dowel on a narrow deck or early wide deck case without body fit thru studs.
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It is my understanding that there is a modification which can be done to the narrow deck cases which installs a bushing or pin which straddles the joint between the two case halves. This helps to prevent the fretting situation which requires the milling of the case haves to correct. I believe that this is one of the things which were done to increase the TBO from 1200 to 2000 hours. Yes changing the valve diameters was also one of the changes.[/UO]


The top picture is my 150 narrow deck. And the bottom picture is a freshly overhauled 160 narrrow deck. Notice the extra bushing around the center main thru stud. Is this what you’re referring to Skywagon?

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Craig, Yes that is it. Without that bushing the case halves can work against each other (fretting) causing a wearing away of some material. Then the next time that the through bolts are torqued the main bearings get pinched below minimum tolerances.
 
Just so you know, those spot faced cylinders you have are not compatible with the cylinder base plates to go to 160 hp....you'd need new narrow deck cylinders without the spot face, longer studs, and a set of base plates to go up 10 hp.....I feel it's not worth the expense.
 
If I went from my narrow deck to wide deck with 160 HP cylinders (and any other misc parts changes), is that just a logbook entry? How do I deal with the data plate, currently A2B which would change to B2B?
 
If I went from my narrow deck to wide deck with 160 HP cylinders (and any other misc parts changes), is that just a logbook entry? How do I deal with the data plate, currently A2B which would change to B2B?

Gord,

no, a widedeck has an A in the serial number. Go to Wikipedia and look up the O320, they have a nice list of the variants of each engine. My understanding is that if you have one model, and convert to anorther, you need a second data plate (depending on the changes).

don
 
LyCon has an STC but you can also do it IAW the parts manual and TCDS and there is a service bulletin for stamping a C on the data tag for converting from one model to another. Some old threads on this site about it as well.
 
LyCon has an STC but you can also do it IAW the parts manual and TCDS and there is a service bulletin for stamping a C on the data tag for converting from one model to another. Some old threads on this site about it as well.
I installed a PA-18 with a 160 hp on floats. The 160 was installed with an STC which was limited to land plane only. The engine was converted from 150 to 160 with no 337 or STC records. I checked with the well known engine overhaul facility and they verified what Steve says about using the parts manual along with the TCDS. I solved the landplane limitation by getting a field approval limiting the engine to 150 hp. This was done by placing a new red line on the tach at the 150 hp rpm. With the prop which was on the plane, it wouldn't turn over the 150 hp rpm anyway. So in the end we still had the 160 hp with no limits other than a different red mark on the tach which was only relevant at full power in level flight.

Gordon, If needed I can show you a copy of this FA. You may be able to use it to assist in getting your own FA for your -12.
 
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