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  #11  
Old 12-29-2019, 09:40 AM
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rocketbob rocketbob is offline
 
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I would stick a camera in there first, and look for any excessive scratching of the cylinder wall. Could be a pin plug or broken ring. But if you're ready to pull it off, why not.
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N9187P PA-24-260B Comanche, flying
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  #12  
Old 12-30-2019, 05:10 AM
kaweeka kaweeka is offline
 
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I pulled the cylinder yesterday and took a few photos. To my untrained eye it looks and feels pretty good. I can see crosshatching from the machining and some alterations in color and sheen but cannot feel any defects in the cylinder wall. The combustion chamber shows lead deposits and evidence that I typically run LOP and again, to my untrained eye, looks otherwise unremarkable. The rings were not aligned so as to let compression through. I see no defects or feel anything unusual. All in all not what I expected to see. See the link to the pictures and thanks again for everyone's input and guidance.

https://www.flickr.com/gp/184001592@N03/YT60JC
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  #13  
Old 12-30-2019, 06:10 AM
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rocketbob rocketbob is offline
 
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The ring gaps are pretty closely aligned. Cylinders look glazed. If it were mine I would clean the piston up a bit, knock the glaze off with a ball hone, and put it back together with new rings.

Its been my experience with any type of Superior cylinder that they lose crosshatch around 750 hours.
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N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #14  
Old 01-01-2020, 06:10 AM
kaweeka kaweeka is offline
 
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I'm reading about Lycoming's recommendation about using a torque plate whenever a cylinder is removed. I have not, and only rotated the crankshaft enough to get the piston pin out. Cylinder arrives tomorrow. Should I be concerned that the main bearings could have slipped? I have an A&P helping me but he didn't even mention the torque plate and says I should keep my W100+ in the engine for break in. I'm thinking that's not right and getting kind of concerned I need some better oversight.
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  #15  
Old 01-01-2020, 07:23 AM
lr172 lr172 is offline
 
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Quote:
Originally Posted by kaweeka View Post
I'm reading about Lycoming's recommendation about using a torque plate whenever a cylinder is removed. I have not, and only rotated the crankshaft enough to get the piston pin out. Cylinder arrives tomorrow. Should I be concerned that the main bearings could have slipped? I have an A&P helping me but he didn't even mention the torque plate and says I should keep my W100+ in the engine for break in. I'm thinking that's not right and getting kind of concerned I need some better oversight.
You'll get varying opinions on the torque plates. Mike Busch says your engine will fall apart if you take a cylinder off, so many accept that as fact. While a torque plate is a good idea, it is not necessary in my opinion. However, I do use washers and snug the nuts down if the cylinder is off for a significant amount of time, assuming that the cylinder is on the side of the bolt that slides through the case (in my engine, the bolts are threaded into the case on one side). 1000's of A&Ps remove cylinders every year without torque plates. If this were a real problem, each top overhaul would result in failed bearings a few months later.

After a hone, that cylinder needs a break in. This means to avoid synthetic oils and any oils with additive packages. Philips 20w50 will be fine for break in. It is pure mineral oil but has an AD additive. However the AD will not hamper ring seating; It is the antifriction additives that are the problem. Not sure where you are located, but 100 weight oil for the winter is probably a bad idea. No Cam gaurd during break in.

The + in W100+ means that it has an antifriction additive package and should be avoided during breakin. W100 or W80 are recommended for breakin.

Larry
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Last edited by lr172 : 01-01-2020 at 07:38 AM.
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  #16  
Old 01-05-2020, 08:17 AM
kaweeka kaweeka is offline
 
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New Superior Millenium cylinder went on yesterday with 9:1 compression. I checked ring gap as directed, oiled up the cylinder and piston. Pretty straight forward with the oversight of experience and, yes, after repeating over and over that I would not forget the cylinder base seal, I forgot it! Lucky my oversight committee pointed this out before I went too far. Man, is it easy to get distracted or overly focused and miss something. I bled down the lifters per instructions but note the pushrods from the previous cylinder are now too long. Got the exhaust rocker on with great difficulty but had no clearance at all. Couldn't get on the intake. My current rods are 73413 listed at 11.936". I need shorter rods and could go to the 73411 at 11.882 but that only gives .054" difference. Valve clearance is .28-.80. Something isn't adding up. Anyone had this experience before? Should I re-bleed the lifters just to be sure? I would love to speak to someone about it.
Thanks, as always, for the benefit of everyone's experience.
David
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  #17  
Old 01-05-2020, 08:29 AM
jabarr jabarr is offline
 
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You never mentioned if your engine had 9:1 pistons before. Hopefully that’s what came out?
Make certain lifters are completely drained.
Valve clearance is .028-.080 (not .28-.80)
You must take into account the rocker ratio. Pushrod length change doesn’t = valve side change.
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  #18  
Old 01-05-2020, 08:59 AM
kaweeka kaweeka is offline
 
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I checked with the original builder before buying the piston. Red faced over reading the valve clearance without glasses on. Thanks. Does anyone have a collection of rods to swap for mine? I just need the 2 for #1 cylinder. I guess I’ll have to just try to see which one fits.
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G3x touch
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Last edited by kaweeka : 01-05-2020 at 09:45 AM.
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