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  #11  
Old 12-28-2016, 09:55 AM
ppilotmike's Avatar
ppilotmike ppilotmike is offline
 
Join Date: Jan 2010
Location: Denver, CO
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Default Advice?

..so, for us guys who haven't yet ordered or installed our engine and prop combos yet, is there something we can do to make sure the engine prop combo we buy is "correctly" clocked? You mentioned that the original setup you had was clocked to allow hand-propping. Is there a way to specify that an engine be set up properly for the 2-bladed Hartzell combo? When ordering a new prop and engine together, can we be sure that it has been properly clocked, or is this something that the builder must do?
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  #12  
Old 12-28-2016, 09:59 AM
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Lenny Iszak Lenny Iszak is offline
 
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Location: Palm City, FL
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Default

Storch,

Thanks for that post!
I've balanced my prop to .01ips and ran a few vibration surveys in flight with my balancer. My engine is smoother at 2700 than at 2360 rpm. I bought all new vibration mounts (i have the not so good VIP mounts, got Lord mounts now), but haven't installed them yet to see the difference.
My half order vibration in flight is .07ips at 2700rpm and .13ips at 2360rpm.
What kind of numbers were you seeing on your spectrum?
Check out the spectra below. The dotted lines are set at half order vibration.

Lenny


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  #13  
Old 12-28-2016, 10:17 AM
Dorfie Dorfie is offline
 
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Location: Lexington, KY
Posts: 409
Default No.1 Crankpin identification

SI 1098G refers to No.1 crankpin from which all other bushing locations are referenced, but does not say how to identify this crankpin.
Is it marked on the prop flange? Something else?
Please help.
Thanks.
Johan
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  #14  
Old 12-28-2016, 10:27 AM
barryrv10 barryrv10 is offline
 
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Location: Fl
Posts: 111
Default New Bushings

Hi Storch, I have the same problem that you had and want to re-clock my prop. Did you have to buy new bushings, or could you have used the old one's? I see they come in oversizes; how did ya know if you could use the stock size or oversize. Thanks Barry
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  #15  
Old 12-28-2016, 11:08 AM
climberrn climberrn is offline
 
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Location: Carson City, NV
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For the people with an IO-360 and WW prop, the prop can be clocked in any position without changing the bushing. The oversized bushing positioned the flywheel, but will fit all the holes on my prop hub.

The best way I can describe the vibration I felt was a deep shake. Even though the balance came out to .04, then .01 IPS, I continued to feel the vibration. Was told the Grumman tiger needed to be clocked a certain position for the same reason.

The best reason we could figure out with the 4 cylinder engines is the highest load on the prop is on the downward movement. With the lightweight prop, it was accelerating when the pistons fire, then decelerates on the down pass. Caused a deep feeling shake.

Not an engineer, but it really made a difference on my plane. Once again, YMMV.
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  #16  
Old 12-28-2016, 11:35 AM
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mburch mburch is offline
 
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Quote:
Originally Posted by Storch View Post
You cannot remove and install the bushings without a special tool. We tried all the homemade remedies. There simply is not enough clearance between the backside of the crankshaft flange and the engine. I finally located the tool at Lycoming. Its a ST-115 (Special tool). They will not sale it or rent it to you but Van Bortel-Air Power will because they are an authorized Lycoming dealer. I called them, gave them the part number and it was at my place in a few days. Costs-they charged me $1354.00, but refunded it when I returned the tool. Rental cost-$100 per month plus shipping. The tool makes it a snap.
Now I'm very curious... what does this super special tool look like?
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  #17  
Old 12-28-2016, 11:59 AM
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Plummit Plummit is offline
 
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Default

What if you have a 3-blade prop? Is that immune form this phenomena or???

I remember that the early Cirrus had a vibration problem with the old 4-point engine mounts. Apparently that was solved with a 5-point mount IIRC.

~Marc


Quote:
Originally Posted by climberrn View Post
For the people with an IO-360 and WW prop, the prop can be clocked in any position without changing the bushing. The oversized bushing positioned the flywheel, but will fit all the holes on my prop hub.

The best way I can describe the vibration I felt was a deep shake. Even though the balance came out to .04, then .01 IPS, I continued to feel the vibration. Was told the Grumman tiger needed to be clocked a certain position for the same reason.

The best reason we could figure out with the 4 cylinder engines is the highest load on the prop is on the downward movement. With the lightweight prop, it was accelerating when the pistons fire, then decelerates on the down pass. Caused a deep feeling shake.

Not an engineer, but it really made a difference on my plane. Once again, YMMV.
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  #18  
Old 12-28-2016, 12:58 PM
climberrn climberrn is offline
 
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Location: Carson City, NV
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Actually, Dayton has a Catto 3 blade prop, with an O-320 and told me about is. If I remember right, he had this problem also.
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  #19  
Old 12-28-2016, 01:37 PM
Storch Storch is offline
 
Join Date: Dec 2016
Location: South
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Default Vibration-bushing size

Quote:
Originally Posted by barryrv10 View Post
Hi Storch, I have the same problem that you had and want to re-clock my prop. Did you have to buy new bushings, or could you have used the old one's? I see they come in oversizes; how did ya know if you could use the stock size or oversize. Thanks Barry
I purchased new stock size bushings, a little pricey but good piece of mind. Never got a definitive answer on reusing them.I believe I recall the oversize being a greater O.D.- I assume that would be for a repair if the hole had been erroneously enlarged?? Not certain.
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  #20  
Old 12-28-2016, 02:02 PM
Storch Storch is offline
 
Join Date: Dec 2016
Location: South
Posts: 10
Default Vibration-crank pin

[quote=Dorfie;1137256]SI 1098G refers to No.1 crankpin from which all other bushing locations are referenced, but does not say how to identify this crankpin.
Is it marked on the prop flange? Something else?
Please help.
Thanks

Yes, I had the same question. I did not find any identifying marks. Try as we did to understand the location of the Lycoming 1098G "No.1 crank pin" we could not do it with absolute certainty. However with our new engine-prop clocking combination, the new placement of the bushings naturally fell into place.What we did was determine the physical location of where each new bushing placement (in the crankshaft flange) would be according to our new prop location.We did not have to change all the bushings. The new position of the prop allowed some of the existing bushings to remain in place. Then going by where the prop needed to be (in relationship to the crankshaft flange) we simply placed the bushings in the respective hole. To achieve the desired new reclocking position we only had to move the prop one hole counter clockwise as viewed from the front of the airplane looking aft. Thinking it through lead us down the this placement path and it worked perfectly.
It did require quite a bit of head scratching.
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