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05-29-2016, 07:56 AM
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Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,530
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Quote:
Originally Posted by lr172
That is Cam whip.
Larry
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Okay:Cam whip. Hereafter, whenever two VAFers have a disagreement on the forums that grows heated, this shall be the official call-out. "Oh yeah? Don't like my views on downwind turns/primer/automotive conversions/pinhole fillers?! You and me - out back behind Doug's website. You need some cam whip, buddy, and I got some right here for ya!"
-Stormy
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05-29-2016, 08:28 AM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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Quote:
Originally Posted by Bill Boyd
Okay:Cam whip. Hereafter, whenever two VAFers have a disagreement on the forums that grows heated, this shall be the official call-out. "Oh yeah? Don't like my views on downwind turns/primer/automotive conversions/pinhole fillers?! You and me - out back behind Doug's website. You need some cam whip, buddy, and I got some right here for ya!"
-Stormy
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the first thing I thought of when I heard it was the "Orange Whip" that John Candy ordered in Blue Brothers.
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
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05-29-2016, 08:30 AM
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Join Date: Nov 2006
Location: Tampa, Florida (KVDF)
Posts: 491
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Quote:
Originally Posted by Steve Melton
I don't remember hearing those noises when rotating my engine to check mag timing. If I had I would have remembered.
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Steve thanks for the response. I see you have a roller camshaft. I'm not sure the dynamics of that but I don't believe they opporate the same way as my tapet/plunger opporated camshaft, I could be wrong though?
Thanks
Bill
__________________
RV6A flying as of November 8, 2016. N717WK
Finishing a RV10
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05-29-2016, 08:33 AM
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Join Date: Nov 2006
Location: Tampa, Florida (KVDF)
Posts: 491
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Quote:
Originally Posted by lr172
That is Cam whip. I noticed it after I rebuilt my engine and spent two days trying to figure out what I did wrong. One of the cam lobes operates two different valves on opposite sides of the engine. At a certain point in it's (the cam) rotation, the opposing forces from the valve springs transfers from one valve train to the other. At this moment the cam trys to reverse direction and gives up it gear lash and causes the click. It is insignificant and unnoticeable at any meaningful RPM, but quite noticeable when turning by hand. As you showed in your video, it always happens at the same place(s).
Larry
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Hi Larry thanks for the response. I did see your thread on the subject. I still wasn't sure if we had the same phenomenon happening. Glad you're able to confirm we are hearing the same things and it is in fact just cam whip.
Thanks
Bill
__________________
RV6A flying as of November 8, 2016. N717WK
Finishing a RV10
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05-29-2016, 09:34 AM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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Quote:
Originally Posted by William
Hi Larry thanks for the response. I did see your thread on the subject. I still wasn't sure if we had the same phenomenon happening. Glad you're able to confirm we are hearing the same things and it is in fact just cam whip.
Thanks
Bill
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The fact that your noise went away when you pulled the rockers, confirms it is in the valve train and should eliminate all other accessory case related noises. It is hard to diagnose from a video, but it sure seems like Cam whip to me. Just confirm that it happens in the same prop position each time. It is a known anomaly; It's just foreign to us guys with auto experience, as it's not replicated there.
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
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05-30-2016, 06:54 AM
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Join Date: Nov 2006
Location: Tampa, Florida (KVDF)
Posts: 491
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Quote:
Originally Posted by lr172
The fact that your noise went away when you pulled the rockers, confirms it is in the valve train and should eliminate all other accessory case related noises. It is hard to diagnose from a video, but it sure seems like Cam whip to me. Just confirm that it happens in the same prop position each time. It is a known anomaly; It's just foreign to us guys with auto experience, as it's not replicated there.
Larry
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Hi Larry it's definitely happening at the same spot each revolution. That sound just sent chills down my spin. Now that you mentioned cam whip and what that is it makes sense. I will be putting the cylinders back on next week and use a stethoscope to confirm this. Did you happen to video your "cam whip sound"?
Thanks again
Bill
__________________
RV6A flying as of November 8, 2016. N717WK
Finishing a RV10
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05-30-2016, 05:22 PM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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Quote:
Originally Posted by William
Hi Larry it's definitely happening at the same spot each revolution. That sound just sent chills down my spin. Now that you mentioned cam whip and what that is it makes sense. I will be putting the cylinders back on next week and use a stethoscope to confirm this. Did you happen to video your "cam whip sound"?
Thanks again
Bill
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I did not, but I remember it sounding very similar to the impulse coupling letting go at TDC and from the same area. While I was diagnosing it with a stethoscope, I pinpointed the sound to accy case area. Once I learned what cam whip was, it made sense and confirmed things for me. The noise comes from the cam gear as it revereses it's lash, if you will, and the cam gear is in the accy case.
The sound from your video was very similar to what I heard.
I also did some layout of the cam action and confirmed that the position of the crank when the sound(s) occurred were where the cam lobe was transitioning from one lifter to the other. Further, the detail came from Mahlon; A trusted source.
Good luck
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
Last edited by lr172 : 05-30-2016 at 05:25 PM.
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08-12-2020, 01:42 PM
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Join Date: Feb 2005
Location: LSGY
Posts: 3,199
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Cam whip
Just ran into this myself, and thought I'd upload a video with the "cam whip" sound on my mattituck io-360 engine.
https://youtu.be/qamE32QTe7I
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