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08-29-2016, 07:25 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by rv6ejguy
I'm glad you also posted about safety precautions around the spinning prop- this cannot be stressed enough. Maybe sure one hand is always on something back near the firewall while holding the timing light with the other hand to limit travel towards the prop and stabilize your body. When clearing the prop area, I always have one hand on the wing leading edge as well.
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Here's a big fat safety tip.
Most of the household step stools and short stepladders are unsuitable for this task. It's not easy to balance on them while in the prop blast, and they are so light that it can feel like they are going to blow out from under your feet.
Long time ago, I needed a perfectly flat, warp free surface for template reference when carving a prop. I built this one using 3/4" thick MDF board, sewn together with drywall screws:
Later the box became a work platform, a place to stand comfortably alongside a fuselage or engine compartment. It is absolutely wonderful as to a place to stand when using a timing light on a running engine...solid, stable, and flat. These days I keep it at the hangar and use it any time it might be more comfortable to elevate myself 16", or as an intermediate step between the floor and the wing.
Highly recommend that you spend a pleasant hour or two building one for yourself. It's just a single sheet of MDF and a box of cheap screws. Top, two sides, two ends, and two ribs. Cut handholds in the ends. You'll love it.

__________________
Dan Horton
RV-8 SS
Barrett IO-390
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08-29-2016, 08:37 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Great tip Dan. Thanks. Can't be too careful here.
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08-29-2016, 09:43 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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However, tape and a sharpie allows you to move the timing mark to a much safer location so you don't need to hover over the engine. last time I did it was off on a the left side of the engine in a very convenient (and safe) position. No need for a step stool.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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08-29-2016, 10:17 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by Toobuilder
However, tape and a sharpie allows you to move the timing mark to a much safer location so you don't need to hover over the engine. last time I did it was off on a the left side of the engine in a very convenient (and safe) position. No need for a step stool.
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Yep------this is how we did it, feet flat on the ground instead of a stool or ladder.
Quick and easy to make your own timing mark------ after setting the factory mark as needed, pick a spot that is convenient and easy to see and created your own pointer and timing mark.

__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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08-29-2016, 04:38 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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All good ideas guys. Putting a new timing mark 90 degrees to the original and adding a witness mark or pointer 90 degrees from the case split can at least keep you feet on the ground when verifying initial timing.
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08-29-2016, 10:14 PM
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Join Date: Nov 2011
Location: Calgary, AB
Posts: 126
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Hidden CPI control box
I hid mine away. The new Guardian Avionics iPad mini dock is mounted in the center of my panel. It took a little effort to carefully hack up the mount but it turned out decent.
Once everything is set up I don't think I will need to see the CPI box on a regular basis but it's really easy to access should the need arise.
The timing has not been set with the light yet but everything works well during my ground runs so far.
[IMG]  [/IMG]
[IMG]  [/IMG]
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VAF Donation made Feb 2020
RV-10 C-GNCX Flying and LOVING IT!
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08-30-2016, 07:11 PM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by CDN
...The timing has not been set with the light yet but everything works well during my ground runs so far...
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Your installation looks great. Its cool to see the innovative ways people are mounting the CPI boxes as this system gains momentum.
It appears that you are not flying yet and I assume that you will set the magnet position before you do, but I wanted to address your quote above for the benefit of the group.
With the CPI it is possible to get the engine to fire "right out of the box", then tune it to a buttery smooth idle with a few presses of the advance/retard keys without setting the magnet position. This is fine if you just want a quick ops check and doing so does not hurt a thing. HOWEVER! Without setting the magnet position accurately, you have no reference basis to adjust timing in flight. The timing values shown on the screen will be completely meaningless and could be off by 10's of degrees.
The magnet position takes only seconds to set (making and mounting the timing pointer is the toughest part), and only has to be done once. Is is the mechanical relationship between the magnets you installed and the position of the hall sensor, and is unique to your engine. Once established, you write the number in the logs and should never need to touch it again.
So the bottom line is simple: DONT FLY WITHOUT SETTING MAG POSITION! Tuning idle "by ear" is fine, but not on takeoff roll.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
Last edited by Toobuilder : 08-30-2016 at 07:14 PM.
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08-31-2016, 07:40 PM
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Join Date: Nov 2011
Location: Calgary, AB
Posts: 126
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Quote:
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So the bottom line is simple: DONT FLY WITHOUT SETTING MAG POSITION! Tuning idle "by ear" is fine, but not on takeoff roll
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This information is imperative for safe flight. Today I used the timing light and the MAG POS was set to 91 from the factory setting of 80. As Toolbuilder said the timing could be off by 10s of degrees and still be buttery smooth. In fact, there was no noticeable difference at 1000 to 1200 rpm between the factory setting and the tuned setting. 11 degrees can make a significant difference at higher power settings.
__________________
VAF Donation made Feb 2020
RV-10 C-GNCX Flying and LOVING IT!
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11-22-2016, 07:04 AM
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Join Date: Feb 2005
Posts: 571
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I just received my CPI from Ross. Have a lot of other "stuff" to do to my Rocket in parallel with the CPI install, so I thought I'd ask the community what they think about harmonic and balance issues while I'm at it.
Ross believes there should be no problem but I'm wondering what everyone else thinks about the long range effects of removing the magneto cush drive/drive gear and bearing, etc.? In my case, I'm planning on one side only and staying with a Slick on the left side. Any ideas about how problematical (or not) this might be from an engine balance and harmonic viewpoint?
Lee...
__________________
Lee Logan
Ridgeland, SC (3J1)
F1 Rocket #160 flying
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11-23-2016, 09:29 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Until someone else jumps in and tells us different, I'm going to go out on a limb and say that the 540 will only benefit from less geartrain mass. There is no balance shaft back there and the crank has pendulum dampeners. Im curious to see if anyone can tell me differently because my engine is apart now and I'm seriously considering leaving out one of the idler gears and the fuel pump pushrod. Since I'm going with the SDS EFI system I only need to drive the cam. All the other hardware used to drive accessories can stay on the shelf in a box as far as I'm concerned.
Of course there is also a long history of 540's flying with the magnetos removed in favor of other EI systems.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
Last edited by Toobuilder : 11-23-2016 at 10:23 AM.
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