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-   -   SDS CPI Tricks and Tips (https://vansairforce.net/community/showthread.php?t=147941)

Toobuilder 03-23-2017 12:29 PM

SDS CPI Tricks and Tips
 
As some of you know I am a very happy user of the SDS CPI product. I have several threads on this and other boards documenting the installation, tuning, and general observations of CPI, and I will continue to help out when I can in the future. I also get PM requests for help and am happy to do so. In the spirit of useful information I thought I would throw together a quick list of common CPI errors and installation tips in this thread.
Keep in mind that this thread is intended to be CPI specific, and covers the problems/tricks I have seen. In many cases, these are covered clearly in the manual but consider this a “foot stomp” requiring extra attention.

Magnet position: The CPI needs to see the synchronization magnet before it derives the firing angle. The magnet position IS UNIQUE TO EVERY INDIVIDUAL ENGINE! Despite the fact that there is a beautiful machined billet hall sensor mount and a precision magnet drill position fixture, the relationship between the engine’s TDC, hall sensor and magnet location on the ring carrier is subject to significant variation. There are a lot of machined holes between the engine and CPI components that define this relationship, so that means a potential for lot of “tolerance stackup”. Also keep in mind that even in a perfect world, there will still be a different magnet position between the first and second pickup of the dual hall sensor (because one is further away from TDC than the other), and the single hall sensor, which will roughly split that difference. Yes, the default magnet position is close, and you can quickly adjust the “timing” with the up/down keys to achieve a beautiful idle, but the timing “value” displayed is likely to be off by 5-10 degrees. It will be worthless as a reference. So to foot stomp this one point – The magnet position MUST be set before flight. Fortunately, it’s a very easy process. Set the engine to a convenient mark on the ring carrier (TDC, 10, 20, etc) and place a pointer in any easy to access point on the engine, make a mark on the gear with a piece of tape and a Sharpie corresponding to the pointer, and grab your trusty automotive timing light (remember those?). With the timing light set up on #1, set the idle RPM advance on the CPI window to match your selected timing mark. Assuming you went with 10 degrees advance, set 10 degrees in all RPM ranges up to about 1200, and zero out the MP advance. Select the magnet position window on the CPI and plug in the default shown in the manual (should be 80 – 90), start the engine and aim the timing light at your temporary pointer. If the mark and pointer align, you got lucky and you are done. If not, simply key the up/down arrow a few times until you drive the mark into alignment. You are now done. Look at the value displayed in the window and record it in your logbook, because it’s permanent to your engine combination. Note that if you have a dual hall mount sensor, you will also have to set the other set of pickups too. DO NOT simply duplicate the mag position setting from one CPI into another. Setting the magnet position takes only seconds to do and forms the basis for all other timing, so don’t skip it.

Drilling the ring carrier: Drilling the holes for the magnets is easy with the provided drill guide. So easy, it can be done without removal from the engine in many cases. That said, the old adage to “measure twice and cut once” applies here. It’s a bit hard for some of us to get our head around the relationship between the sync and trigger magnets and their location around the ring carrier, and I’m not the only one who has a few “extra” holes… My advice to all of you out there is to slow down, study the installation manual, and when you think you are ready to drill, STOP, and use a Sharpie instead. “Drill” and label your holes with a Sharpie and then go to bed. The next day, compare your artwork with the illustration in the manual with a fresh set of eyes. If it matches, fire up the drill and go for it.

Ignition tuning: Set with the defaults, the CPI provides all the performance benefits of any electronic ignition and works beautifully. However, unlike the other offerings, CPI offers essentially infinite adjustment of timing so that you can tailor it to YOUR airplane and YOUR mission. Despite the myriad of adjustments, you do not have to be a test pilot to find the optimum setting. I have found that one of the clever features of the CPI has an unintended benefit – a way to safely “backdoor” test settings. The LOP feature instantly adds a user definable advance value with the flip of a switch, which also means that you can instantly REMOVE this value if something doesn’t go the way you like. This provides a very safe way to sneak up on an advance setting in flight because it gives you an instant return to a known, safe condition.

To illustrate a very conservative approach to finding a “ROP, cross country cruise” (for example) setting: On the ground, set up the RPM advance to max out at your data plate setting (25 degrees, for example), and zero out (disable) any MP advance. Now you are flying with your engine manufacturers known “safe” condition and can play from that position of certainty. Climb to altitude (7500, for example) and set power, mixture, and let it stabilize at speed. Once satisfied with your “normal” speed, record that value, and all other pertinent engine values, as well as your timing as shown on the CPI window (should be 25, in this example). With data recorded, select the LOP window on each CPI and set it to “1” (degree). Now flip the LOP switch and see what happens. If everything looks good, let that setting stabilize (at least 5 minutes) and record the timing (now 26), and the speed. If you want, grab the temps too. With the switch still active, simply select one more degree (now “2”), let it stabilize, record, and repeat in 1 degree increments until you see the speed peak, then decline. The total advance setting that corresponds to peak speed is now your target for your yet to be built “final” advance curve. What this is doing is finding optimum engine output for that mixture, tailored to YOUR airframe, engine and prop combination. Once your final advance curve is built and you once again are cross country, high and ROP, you can use the same technique to find your “LOP” setting. The only difference is that you will now be at a RPM and MP derived “optimum” advance (let’s say it’s 31 degrees) with the LOP switch INACTIVE. You will pull the mixture to your typical LOP setting, the speed will sag a bit (as usual) and the FF will plummet. Once again, select the LOP window on each CPI and input 1 degree advance. Record your (stabilized) speed and then activate the LOP switch. You will see a bit of the speed come back shortly, so as before, add advance and find the peak speed. The optimum advance setting you find is now your “permanent” LOP switch setting. In my case, my Rocket regains 3 knots with the flip of that switch when LOP.

That’s all I have for now. If I (or anyone else) thinks of any more they should drop it here. CPI is one of the newest ignition products on the block so the pool of knowledge is not as deep as others. Hopefully, this thread will serve as a resource for current and future CPI cusomers.

tim2542 03-23-2017 01:39 PM

Another happy customer
 
I made the mistake of switching the control box via my "mag" switch instead of the coils. Obviously if you want to read the tachometer while testing the other ign system you need the control box running. A simple oversight but it required me to re-wire the system.

The other thing I ran into is the color dye on the tiny magnets is easily removed, so just be careful when handling them you don't wipe it off. It's easy to sort out if you do remove it but requires additional head scratching.

I curious why the instructions advise not to use a timing light with built in advance. That's the only type I own and it worked just fine.



Tim Andres

rv6ejguy 03-23-2017 03:06 PM

Quote:

Originally Posted by tim2542 (Post 1160174)
I made the mistake of switching the control box via my "mag" switch instead of the coils. Obviously if you want to read the tachometer while testing the other ign system you need the control box running. A simple oversight but it required me to re-wire the system.

The other thing I ran into is the color dye on the tiny magnets is easily removed, so just be careful when handling them you don't wipe it off. It's easy to sort out if you do remove it but requires additional head scratching.

I curious why the instructions advise not to use a timing light with built in advance. That's the only type I own and it worked just fine.



Tim Andres

Some knob type timing lights don't read correctly when used with waste spark type systems since sparks are happening at double the "normal" frequency.

Best to use a cheap, dumb Walmart special.

rv6ejguy 10-13-2017 07:56 PM

CPI Self-Test Spark Feature
 
I thought I'd shoot this short vid today while I was testing some new coil modules. Some people might find this helpful if troubleshooting:

https://www.youtube.com/watch?v=SAooHa0PhdA

maus92 10-14-2017 05:36 AM

I would love to see a video of the timing light in action - I'm still a bit confused about the process on an airplane with an engine running and a spinning prop..

gasman 10-14-2017 10:05 PM

Quote:

Originally Posted by maus92 (Post 1210914)
I would love to see a video of the timing light in action - I'm still a bit confused about the process on an airplane with an engine running and a spinning prop..

I agree. I find it hard to picture how you can time within 1 deg. with the timing light flashing on two lines that are only 1/8th thick leaning over a running motor standing 30 inches from a spinning prop and trying to view straight on over 24 inches away...........:eek:

Toobuilder 10-14-2017 11:45 PM

The same way you did it on your Camaro or Mustang back in high school auto shop. Aim the light at the marks and when it lines up, you're done.

Larry DeCamp 10-15-2017 03:51 AM

Mount the timing light
 
For the faint of heart ( me included), mount the timing light like a prop balance sensor on the case and use your cell phone to video the timing mark. You only need to do it once.

maus92 10-15-2017 08:09 AM

Quote:

Originally Posted by Toobuilder (Post 1211119)
The same way you did it on your Camaro or Mustang back in high school auto shop. Aim the light at the marks and when it lines up, you're done.

I wasn't aware that Camaros or Mustang had props - I must have missed that class :) (We actually didn't have an auto shop at my high school.)

The suggestion about mounting the timing light similar to a prop balancer, then using a cell phone camera (I might use a GoPro) seems like a safer procedure.

rv6ejguy 10-15-2017 08:39 AM

I've taped the gun to the top of the engine and put an elastic around the trigger. An overcast day works best and I usually also put a strip of white or silver tape on the flywheel to reflect better.

On our Continental, I also built a sheet metal tab to project the case split line closer to the prop hub.

We'll hopefully be running a test 360 soon. I'll shoot a video then.

I like the smart phone idea though too.

Maybe binoculars if your eyes aren't as good as they used to be?

Norcalrv7 10-15-2017 09:11 AM

I made my own timing pointer off the front of my baffling, and bent it until it matched the TDC marks on back side of the ring gear. With the airplane chocked in the evening time, I was able to stand in the seat and see the marks pretty easily from the cockpit.

Mike S 10-15-2017 09:42 AM

Make a timing mark where it suits your needs
 
We set the engine-- not running-- to TDC using the starter pln setup, then created a timing mark on the flywheel where it was safest/easiest to see using masking tape and a Sharpie, then made up a pointer for that mark using a bit of safety wire held in place with tape.

There is a photo in the thread "My CPI installation" in this forum, a search will bring it up, if the following link doesnt work.


https://lh3.googleusercontent.com/GN...=w1184-h889-no

Toobuilder 10-15-2017 10:39 AM

Quote:

Originally Posted by maus92 (Post 1211169)
I wasn't aware that Camaros or Mustang had props - I must have missed that class :) (We actually didn't have an auto shop at my high school.)

The suggestion about mounting the timing light similar to a prop balancer, then using a cell phone camera (I might use a GoPro) seems like a safer procedure.

Sorry, I didnt consider the prop because you dont need to have your eyeball exactly in plane with the ring carrier. If you are thinking your ear is a fraction of an inch ftom the prop,it does not need to be. Follow Mike S' example and place the pointer wherever its convenient on the case (preferbaly low and to the side), and you can keep your head well back from the prop arc. Use a piece of masking tape on the ring carier in the general location of the mark, a red sharpie for your mark, and a black one either side and it is very easy to see from 24 inches away (just the like the balancer on your Camaro or Mustang).

gasman 10-15-2017 10:49 AM

You might want to confirm the accuracy of your factory timing marks before you trust them.......
http://www.aircraftspruce.com/catalo...ickkey=3240965

Or just purchase the pin..... http://www.aircraftspruce.com/catalo...ickkey=3240965 and use your smart level or phone.

jump4way 10-15-2017 12:23 PM

A video showing how the timing light is used would be very informative to me also. I?m struggling to visualize the entire process.

Toobuilder 10-15-2017 09:58 PM

It's harder to explain than do. But you "move" the timing mark with the Magnet Position window key. Add one degree and if the timing mark moves closer then you are doing it right. You simply add or subtract until the mark aligns. The resulting magnet position is "your" permanent setting.

maus92 10-31-2017 08:40 PM

I was reading in the SDS CPI aviation supplement date 8/17:

"The CPI is not waterproof and will not function as designed if moisture invades the enclosure or power/ ground connections are interrupted."

Does this apply only to the controller box which is normally cockpit mounted, and no other components - like the coil pack?

"If you’re installing a single coil pack, remove the right magneto and any gears or bearings which rely on the magneto to hold them in place."

I intend on replacing the left magneto (and impulse coupling) and retaining the right magneto for the time being. Is this possible with SDS CPI systems?

I am so close to pulling the trigger...

rv6ejguy 10-31-2017 08:45 PM

Everything FF is waterproof.

You can remove either mag.

Be sure you have the larger 8 7/16 ID flywheel to be able to use our crank trigger hardware.

Toobuilder 11-01-2017 07:26 AM

Quote:

Originally Posted by maus92 (Post 1215522)
....I intend on replacing the left magneto (and impulse coupling) and retaining the right magneto for the time being. Is this possible with SDS CPI systems?..

CPI/Mag combo's work just fine. Slight difference in LOP timing to compensate for the retarded timing of the magneto, but thats about it.

I will emphasize again that you buy the dual hall sensor on the first go, even if you dont think you are going to add a second system down the line. Its only a few extra bucks and makes it SIGNIFICANTLY easier to add a second system if you change your mind.

logansc 11-01-2017 07:42 AM

Guys: I am one of those like Tim2542 who initially wired my CPI such that I don't have a tach signal on my remaining magneto when I switch the CPI off during "mag" checks. Did I miss the instructions on that? I've been having way too much fun flying the airplane in its new, smoother, better starting life to stop now and work it out. However, as soon as winter arrives, I have a whole list of "stuff" to do and rewiring is one of them.

Is there a wiring diagram that I missed somewhere that will get renew the signal from my mag while still showing the CPI tach signal when I test them individually?

Thanks!

Toobuilder 11-01-2017 08:38 AM

Logan -

The tach signal should continue to function as long as power is going to the brain box. You can do your "mag check" using that function on the box or killing power to the coil pack with the CB. If you are killing the whole system power, I think that's your issue.

maus92 11-22-2017 07:39 PM

So I'm installing my SDS. Found a temporary place for the control box on the lower right sub panel, test fitted the crank sensor bracket, drilled the baffle for the sensor cable, fabbed a shield to deflect a broken alt belt, etc. I've had a 500hr inspection on the right mag which will be retained.

Today I removed the left mag. The spacer is still tightly attached to the case. Before I go to the trouble of removing the spacer and replacing the studs, would there be an issue if I simply left the spacer attached, and bolted the cover plate to the spacer? The would save me the trouble of installing shorter studs.

BTW, what's the torque value for the case bolts? I'm mounting the coil to the top of the engine, and the front bolts loosened to mount the Hall sensor will need re-torquing.

Toobuilder 11-22-2017 08:39 PM

No issue with leaving the spacer except a few ounces, less space and aditional leak potential. BTW, there is no requirement to replace the studs with shorter versions - bolts work just fine for cover plates. Getting the old gasket off is fun, as is removing the studs, but thats a one shot deal.

Mike S 11-22-2017 08:57 PM

Methinks this thread deserves "sticky" status, lots of good info that should be easy to find.

DanH 11-23-2017 05:39 AM

Quote:

Originally Posted by maus92 (Post 1220716)
BTW, what's the torque value for the case bolts? I'm mounting the coil to the top of the engine, and the front bolts loosened to mount the Hall sensor will need re-torquing.

1/4" perimeter bolts: 96 to 108 inlbs
3/8" case studs: 25 ftlbs
7/16" case studs: 35 ftlbs
1/2" case studs: 50 ftlbs

tim2542 11-23-2017 06:50 AM

If you are pulling the left (impulse) mag and leaving the non impulse mag, you should take measures to prevent that mag from accidentally being turned ON while cranking as it will cause a kickback.
You probably knew this already
Tim Andres

maus92 11-23-2017 06:59 AM

Quote:

Originally Posted by tim2542 (Post 1220765)
If you are pulling the left (impulse) mag and leaving the non impulse mag, you should take measures to prevent that mag from accidentally being turned ON while cranking as it will cause a kickback.
You probably knew this already
Tim Andres

I have individual locking toggles. Right now, the only countermeasures I have are: checklist procedures; panel labeling; and pilot knowledge (which is the weak link.) I know that there is a design out there that interlocks the ignition toggles, I need to find it.

tim2542 11-23-2017 07:39 AM

Here you go:
http://www.vansairforce.com/communit...ad.php?t=36272
Post 5 has the links to Bob Nuckolls article and drawings
Tim Andres

maus92 11-26-2017 07:04 AM

The SDS CPI has a weatherpack-type 4 pin connector that joins the coil to a wiring harness to the cockpit controller and power. I want to hard mount the harness side to the rear baffle - is there a mounting accessory for these types of connectors? If I need to fab something, any suggestions?

jump4way 11-26-2017 08:34 AM

I didn?t do this with my install but I wish I had. I think these Deutsch DT connectors are really nice. They have a flange Mount version that could be mounted to the baffle. I?m using these for wing root connectors. They aren?t cheap but they are good quality.

https://www.prowireusa.com/c-3-deuts...aspx?pagenum=3

plehrke 11-26-2017 02:10 PM

Quote:

Originally Posted by maus92 (Post 1221363)
The SDS CPI has a weatherpack-type 4 pin connector that joins the coil to a wiring harness to the cockpit controller and power. I want to hard mount the harness side to the rear baffle - is there a mounting accessory for these types of connectors? If I need to fab something, any suggestions?

Use a band clamp wrapped around the connector and attach to an adel clamp. Mine currently is attached with zip ties but will make more permanent with the band clamp next time the cowl comes off.

rv6ejguy 12-11-2017 12:01 PM

Quote:

Originally Posted by jump4way (Post 1221374)
I didn?t do this with my install but I wish I had. I think these Deutsch DT connectors are really nice. They have a flange Mount version that could be mounted to the baffle. I?m using these for wing root connectors. They aren?t cheap but they are good quality.

https://www.prowireusa.com/c-3-deuts...aspx?pagenum=3

These are nice connectors but the temperature specs listed here are not believable. Looks like multiple typos...:confused:

rv8bldr 12-11-2017 12:38 PM

Quote:

Originally Posted by rv6ejguy (Post 1224889)
These are nice connectors but the temperature specs listed here are not believable. Looks like multiple typos...:confused:

Looks like they missed the decimal points. Maybe -55.0C to +125.0C ?

jump4way 12-12-2017 04:53 AM

The TE connectivity site agrees with -55 to 125C which is the same on the high end as the weather pack connectors that come with the SDS harness and better on the low temperature end. Weatherpack connectors are listed as -40 to +125C. It seems like they should work.

maus92 06-05-2018 07:47 AM

Anybody running their RPM line through a G3X system (GEA24)? I have the pickup on the right mag wired to RPM 1, and the RPM output from the SDS CPI box wired to RPM 2. What config settings do you use?

maus92 06-20-2018 05:04 AM

I am at the point of installing the spark plugs. What is the best way to install the adapters? With the plugs in, or install the adapters first?

I've test fitted the adapters, and they start meeting resistance much sooner than I expected. The aviation plugs have very little until they are tight against the head, ready for torquing. Is the resistance with the (brass?) adapters by design? I don't want to destroy the threads in the head. Also, torque values?

rv6ejguy 06-20-2018 05:21 AM

Since the thread sizes are different, these 2 parts require different torque values. We torque in the adapters first at 25 ft/lbs, followed by the plugs at 18. Use only a small dab of anti seize, don't coat the threads.

maus92 07-06-2018 07:50 PM

OK, getting very close to first run / timing. I am running a split system, retaining the non-impulse right mag, and using the SDS CPI as the left ignition source. The CPI fires all top plugs.

1. I find the supplied documentation to be vague. It needs to be written in a format that holds the hands of dumb / non gear-head pilots like me. A step-wise procedure, sorta like what NASA does for their evolutions would be ideal.

2. What should the timing be for the right mag? 25 BTC?

3. I am deathly afraid of the first start up and kick back. Is this rational?

4. I've ordered this timing light from Amazon. Sufficient?
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

5. Has anyone made of YouTube video of their timing procedure? I've seen some photos of TDC markers / wires, but in my case, the baffling will interfere with setups I've seen. I'm still trying to engineer a solution.

Anybody with experience please chime in with photos / videos!

Toobuilder 07-06-2018 08:05 PM

Set the mag to fire at data plate values, but make sure it is not active on the starter.

Timing marks for the CPI can be placed anywhere convenient. Just put the engine on TDC (or 10, or 20, or whatever degrees), then add a pointer in a convenient location, and mark the ring gear.

If you want to give me a call I'm happy to walk you through it. Send me a PM and I'll shoot you the contact info.

maus92 07-06-2018 09:09 PM

Sealing the aluminum mag hole cover: Permatex Red RTV OK? - or a mag gasket?


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