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Old 11-01-2017, 10:31 PM   #26
Eagle-Mike
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That makes sense...
Loosen all nuts and then torque all new as per overhaul manual
right?


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Old 11-02-2017, 03:01 AM   #27
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Manuel, can you tell us how many hours since latest cylinder removal?


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Old 11-02-2017, 03:23 AM   #28
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Originally Posted by Eagle-Mike View Post
That makes sense...
Loosen all nuts and then torque all new as per overhaul manual
right?

"If it's not broke, don't fix it" Usually very good advice!

Problem is you do NOT know if the engine was not assembled correctly. If built by a good experienced shop or person the assumption is that it is correct. Loosening and re-torqueing could cause a failure worse than a broken stud which is bad enough.

Crap shoot......

Mike B. makes the case for not removing cylinders unless absolutely necessary. Probably good advice. Re-torqueing has the same issues.
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Old 11-02-2017, 03:53 AM   #29
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These guys have an stc to put 10:1 pistons in Mooney's and Cardinals and claim no change in TBO. I've talked to them about my engine before an they were very open and informative. You may want to give them a call and see if they have some insight to whats going on with your engine.
http://thenewfirewallforward.com/lin...r_plus_stc.pdf
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Old 11-02-2017, 12:11 PM   #30
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Well, I know a Cardinal owner who put that mod on his airplane and later removed it. Don't know more than that. And my understanding is that Firewall Forward has had a checkered past as a company. Perhaps the latest incarnation is better.

Best of luck,

Wes
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Old 11-02-2017, 12:23 PM   #31
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Originally Posted by bdalporto View Post
These guys have an stc to put 10:1 pistons in Mooney's and Cardinals and claim no change in TBO. I've talked to them about my engine before an they were very open and informative. You may want to give them a call and see if they have some insight to whats going on with your engine.
http://thenewfirewallforward.com/lin...r_plus_stc.pdf

They stand behind it for 500 hours. Sounds about right
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Old 11-07-2017, 06:17 PM   #32
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I've used fire on tires before but this one was too far off. I don't know exactly how the tube deal worked but @ $10 I don't care.

My nephew has A&P/IA with both large and small aircraft experience. We got a good laugh when he as overheard saying, "I can fix a Boeing 747 but can't fix a ^%$#@#$ lawn mower!"

I suspect most of us have been there-done that?


A lot of shops are required to fill tires in a cage for reasons like this.
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Old 11-07-2017, 06:20 PM   #33
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I read an article somewhere written by a mechanical engineer PHD that basically said a torque wrench is useless and dangerous when replacing a cylinder. Bolt stretch is the only way to measure the torque. Iíll have to dig up that article somewhere. The basic point of the article is that maintainers are way to caviler about replacing cylinders.
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Old 11-07-2017, 06:46 PM   #34
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You can feel the difference of the stretch from the through bolt and stud. The only problem of using stretch is tooling would have to be invented for something like a cylinder and you would have to get Lycoming to come up with some measurements.

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Old 11-07-2017, 07:49 PM   #35
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Quote:
Originally Posted by Lotahp1 View Post
Thatís taking it alittle far for me. When I recommend a cylinder change I donít want a owner to have nightmares of his engine blowing up because he changed a cylinder.
I wish I had not changed my cylinder. It blew up at 13 hours. I am pulling it Friday and I'll know why then (I hope).
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Old 11-07-2017, 10:10 PM   #36
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I read an article somewhere written by a mechanical engineer PHD that basically said a torque wrench is useless and dangerous when replacing a cylinder. Bolt stretch is the only way to measure the torque. I’ll have to dig up that article somewhere. The basic point of the article is that maintainers are way to caviler about replacing cylinders.


I'd like to see exactly how he measured stretch on a cylinder stud.

Maybe a thru bolt......that would be fun.
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Old 11-15-2017, 06:16 PM   #37
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I think the article's point was more to the point about mechanics being too caviler about changing cylinders. It is extremely difficult to get proper torque from an engine that is in service. Things like bolt wear, age, lubrication, and access all being in the way of getting proper torque. The torque wrench method is very flawed but we don't have much in the way of improved methods.
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Old 11-29-2017, 10:00 PM   #38
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Just prior to Reno this year, I changed the four cylinders on my (I)O-360 in the Pitts. I got the cylinders from Allen Barrett (Barrett Precision Engines) and he [along with Kenny at LyCon] said to not reuse the 1/2" nuts used for cylinder hold-downs. The smaller 3/8" could be reused, but not the 1/2". They aren't cheap but I wasn't going to take any chances on reusing the nuts.

Here's my question for all of you, though. Now that Reno is long since past, I'd like to do a thorough inspection of the engine and pull the jugs. Is it general consensus that you can/cannot pull a jug all the way off and not re-ring/hone it? Obviously, I only had a few hours on the engine with Reno anyway. Sure would like to get away from reringing/rehoning if it's ok to do that.

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Old 11-30-2017, 12:57 AM   #39
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The times that I had a cylinder off to fix a valve guide I did not rehone. Just carefully slid the cylinder back on over the piston and rings that it came off of. But I would not mix them up if I pulled them all.

You can pull the cylinder part way off, leaving the piston mostly in the bore and push the wrist pin out, removing the cylinder and piston part mated together. I think that if the piston has an oil control ring "below" the wrist pin that will be hanging out, but by leaving most of the rings in the cylinder you reduce the risk of breaking one.

Best of luck,

Wes
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Old 11-30-2017, 02:12 AM   #40
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Don't replace and hone unless something needs to be replaced.
Those rings are broke in... grammar... IRAN if you must but the rings should fall right back into place like nothing ever happened.
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Old 11-30-2017, 02:37 AM   #41
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If you choose to pull the jugs and wish to keep the pistons in the cylinder it is sometimes difficult to get the wrist pins to slide out. There is a piston pin puller, but I have had good success at removing the pin by heating the piston pin bosses with a hot air gun. Doesn't take that much heat and the pins will slide right out.
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Old 11-30-2017, 08:27 AM   #42
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Quote:
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Don't replace and hone unless something needs to be replaced.
Those rings are broke in... grammar... IRAN if you must but the rings should fall right back into place like nothing ever happened.
Thanks everyone for the replies. Sounds like I'm ok not reringing/rehoning. I just want to give everything a good look over since we were at over 13:1 compression. Early in the race week we had a slight detonation issue while on 100LL. Afterwards, I was on 115/145 octane with no further detonation. Borescoping revealed no apparent damage but I'd like to give the pistons a good look.

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Old 11-30-2017, 05:29 PM   #43
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to me asking about having to re-ring if you take the piston out of the cylinder is really a question about if the rings rotate or do they stay in a fixed position. So if you think they are fixed at the time of install, then that means you have disturbed them upon removal and they will no longer be seated.

Rings rotate on the piston, therefore when you re-assemble them no consideration as to position is required past any other normal consideration.

here is a study on ring rotation:
https://www.highpowermedia.com/blog/...f-piston-rings

I think the bigger issue would be dislodging any carbon or other foreign material around the rings.
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Old 12-01-2017, 01:36 AM   #44
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A young engine should not be too much problem, especially if you dont play with the rings or mark the gaps with a sharpie. An old engine after the rings have gone "square", might have more of a problem of of the rings finding their spot once disturbed.


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