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SDS CPI Tricks and Tips

Toobuilder

Well Known Member
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 several degrees. The engine will run fine, but the displayed timing value will be suspect and therefore worthless as a reference. So to foot stomp this one point – The magnet position should be set to your engine 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.
 
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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
 
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.
 
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..
 
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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:
 
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.
 
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.
 
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.
 
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?
 
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.
 
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/G...pxFy7usTyBfaQI1HOWKE-akuEbVVjaU=w1184-h889-no
 
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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).
 
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A video showing how the timing light is used would be very informative to me also. I?m struggling to visualize the entire process.
 
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.
 
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...
 
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.
 
....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.
 
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!
 
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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.
 
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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.
 
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.
 
Methinks this thread deserves "sticky" status, lots of good info that should be easy to find.
 
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
 
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
 
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.
 
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?
 
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.
 
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-deutsch-dt-.aspx?pagenum=3

These are nice connectors but the temperature specs listed here are not believable. Looks like multiple typos...:confused:
 
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.
 
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?
 
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?
 
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.
 
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/B000EVYH72/ref=oh_aui_detailpage_o00_s00?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!
 
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.
 
Sealing the aluminum mag hole cover: Permatex Red RTV OK? - or a mag gasket?
 
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The Amazon timing light should work fine.

There is no danger of kickback with the CPI with the base timing curve we send it out with. Cranking timing will be after TDC for sure unless you mounted the magnets in the wrong place on the flywheel.

Since there are only a few wires to hook up and a diagram showing where they all go, we're not getting much feedback from people that it's confusing to hook up but we'll take another look at the documentation if you tell us what part was not clear to you.

We'll be doing a series of videos starting next week on a local RV6 outlining initial setup and tuning of an EM-5 system which uses the same hardware FWF and setup procedures as the CPI. I think people will find these informative.
 
The Amazon timing light should work fine.

There is no danger of kickback with the CPI with the base timing curve we send it out with. Cranking timing will be after TDC for sure unless you mounted the magnets in the wrong place on the flywheel.

Since there are only a few wires to hook up and a diagram showing where they all go, we're not getting much feedback from people that it's confusing to hook up but we'll take another look at the documentation if you tell us what part was not clear to you.

We'll be doing a series of videos starting next week on a local RV6 outlining initial setup and tuning of an EM-5 system which uses the same hardware FWF and setup procedures as the CPI. I think people will find these informative.

I have a Lycoming O-360 A1A, retaining the right non-impulse mag.

I had a discussion this afternoon with another builder who has installed the system. He advised to adjust the degree values between 500 RPM to 1200 RPM to 0˚ on the initial startup to set timing, and to enable the right mag (which is set at 25˚ BTDC) prior to adjusting timing value. Also adjusted the Mag Position from 80˚ to 85˚ - do you concur?

As for wiring, that part is not difficult, however the heat shrink on the tefzel leads interferes with full insertion of the leads into the Molex shell. I had to trim some of them, and use a pin tool designed for another type of connector to get them deep enough into the shell to seat properly and make a good connection. Also, the type of signal carried on the tach wire should be described to help configure EFISs.

What is difficult is the initial setup / timing discussion and procedure - it simply is not well explained, particularly for people like me who are only casually familiar with ignition systems:

"STEP 5. Change the MAGNET POSITION value until the timing light reads 10 degrees BTDC." covers a lot of territory, and I was not exactly sure how to setup and measure this until I discussed the procedure earlier today. I *hope* I will be able to set up the pointer properly, and read it. It will involve a ladder to get high enough to see over the baffling, tying down the tail, chocking, etc. I'll be marking the ring gear rather than the flywheel pulley to help with visibility.

Finally, sealing the mag cover - Red RTV ok?

Thanks for responding.
 
Remember that the "0" degree initial timing position works because the engine is really running on the 25 degree magneto in this case, and the "0" (TDC) mark is very prominent on the flywheel. If you have a 10 degree mark, then thats fine too. Not many Lycoming flywheels have the 10 degree marked. The salient point here is the instructions assumed you were going to have the flywheel marked at 10 AND the initial timing programmed at 10. You could do 20 and 20, 15 and 15, 9 and 9... Any value between 0 and 30 is really irrelevant as long as the physical mark/pointer is captured on the flywheel AND the brain box matches that number. You really only are looking to make the actual spark event line up with the physical mark on the flywheel. When the two line up, then your true magnet position is established and you are done with that step forever.
 
I have a Lycoming O-360 A1A, retaining the right non-impulse mag.

I had a discussion this afternoon with another builder who has installed the system. He advised to adjust the degree values between 500 RPM to 1200 RPM to 0˚ on the initial startup to set timing, and to enable the right mag (which is set at 25˚ BTDC) prior to adjusting timing value. Also adjusted the Mag Position from 80˚ to 85˚ - do you concur?

As for wiring, that part is not difficult, however the heat shrink on the tefzel leads interferes with full insertion of the leads into the Molex shell. I had to trim some of them, and use a pin tool designed for another type of connector to get them deep enough into the shell to seat properly and make a good connection. Also, the type of signal carried on the tach wire should be described to help configure EFISs.

What is difficult is the initial setup / timing discussion and procedure - it simply is not well explained, particularly for people like me who are only casually familiar with ignition systems:

"STEP 5. Change the MAGNET POSITION value until the timing light reads 10 degrees BTDC." covers a lot of territory, and I was not exactly sure how to setup and measure this until I discussed the procedure earlier today. I *hope* I will be able to set up the pointer properly, and read it. It will involve a ladder to get high enough to see over the baffling, tying down the tail, chocking, etc. I'll be marking the ring gear rather than the flywheel pulley to help with visibility.

Finally, sealing the mag cover - Red RTV ok?

Thanks for responding.

Thanks, we appreciate the specific feedback and will look at addressing these points.

Red RTV ok for sealing the mag cover plates.
 
Remember that the "0" degree initial timing position works because the engine is really running on the 25 degree magneto in this case, and the "0" (TDC) mark is very prominent on the flywheel. If you have a 10 degree mark, then thats fine too. Not many Lycoming flywheels have the 10 degree marked. The salient point here is the instructions assumed you were going to have the flywheel marked at 10 AND the initial timing programmed at 10. You could do 20 and 20, 15 and 15, 9 and 9... Any value between 0 and 30 is really irrelevant as long as the physical mark/pointer is captured on the flywheel AND the brain box matches that number. You really only are looking to make the actual spark event line up with the physical mark on the flywheel. When the two line up, then your true magnet position is established and you are done with that step forever.


OK, glad you wrote this because I *think* I my mark the flywheel / ring gear is now incorrect for the 0˚ settings. After changing the values to 0˚ for RPMs up to 1200 in the control box, I did not change the mark on the flywheel - which is currently marked at 10˚. Should I change the flywheel mark to 0˚ / TDC to correspond to the new settings I made in the control box?

I'm making a pointer that will align with the case split / TDC, and attach to a baffle mounting screw.

Thx.
 
When you're setting Magnet Position, you can choose any convenient mark you have on the flywheel, 0, 10, 25 etc. as long as you also set RPM timing at the rpm you're checking the same- ie. have a flywheel mark at 10, set RPM timing to 10 at 750, 1000 and 1100 rpm before checking with timing light at 1000 rpm. We want to make sure the module is using that 10 value, not an adjacent one.

Magnet Position is a one-time calibration to tell the CPU the actual offset. Once the timing gun says you're at 10 in this case, you can reset your RPM timing to whatever you want and it will be correct.
 
OK, glad you wrote this because I *think* I my mark the flywheel / ring gear is now incorrect for the 0˚ settings. After changing the values to 0˚ for RPMs up to 1200 in the control box, I did not change the mark on the flywheel - which is currently marked at 10˚. Should I change the flywheel mark to 0˚ / TDC to correspond to the new settings I made in the control box?

I'm making a pointer that will align with the case split / TDC, and attach to a baffle mounting screw.

Thx.

To follow up with our phone conversation, here is a step-by-step for you:

1. Using the top splitline of the case and the timing marks on the REAR of the ring gear, rotate the engine until it is at TDC ("0" degrees) on the compression stroke for #1 cylinder.

2. WITHOUT ROTATING THE ENGINE AGAIN, find a "convenient" place to view the ring gear with a timing light (You suggested somewhere near the starter).

3. Fabricate a pointer from wire or similar and affix pointer to case with the indicator somewhere within this "convenient field of view". Make sure the pointer is very close to, but does not touch the ring gear.
WARNING: Make sure this "convenient" position keeps all parts of your body and equipment well clear of the prop, ring gear, belt, alternator, etc. I grew up with strobe timing lights and for those unfamiliar, the view is "frozen" so the mind can trick you into forgetting stuff is rotating with significant speed. Its very, very easy to reach into an area that looks static, but in fact that prop blade is spinning at idle.

4. Again, without rotating the engine, mark the ring gear with tape and a sharpie so that the pointer and mark are in alignment as viewed from the timing light operator.

5. With the indicator secured, the ring gear marked and the two are in alignment, verify the engine has not turned by inspecting the factory timing marks at the top split line (still in alignment).

6. Make sure the timing light is hooked to the #1 cylinder CPI ignition lead (not the magneto).

7. Fire the engine on the CPI (magneto off). It will run, but it will be labored due to firing at TDC. Turn on the magneto (idle should improve significantly due to the 25 degree advance). Atain a normal idle at ~800 to 1000 RPM. (As Ross suggests, you dont want the idle moving high enough to do a timing shift. In your case, that would occur at the 1300 RPM mark).

8. With the engine running at normal idle, shoot the timing light at your fabricated pointer. Your tape/sharpie mark should be somewhere near that pointer, high or low. If its dead on, then you are done. Document the number displayed in the "Magnet Position" window in your logbook.

8a. If the mark is visible with the timing light but out of position high or low, then have a helper key the up or down arrow on the CPI box while in the Magnet Position window. Simply drive the mark into alignment with your pointer. When aligned, the resulting number in the Magnet Position window is "your" number. Document in the Logbook for future reference.

8b. If your tape/sharpie marks are not even visible anywhere on the ring gear with the timing light then there are a few probable causes (I've done ALL of these):
a). The timing light isnt working
b). The marks you made dont have the proper contrast for the ambient lighting
c). The timing light is hooked to the wrong spark plug lead
d). The CPI programming is off for the RPM or MP advance values (the guage window will show current advance - should be "0" in your particular case)

If all else fails, give me a call and we'll work it out.
 
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When you're setting Magnet Position, you can choose any convenient mark you have on the flywheel, 0, 10, 25 etc. as long as you also set RPM timing at the rpm you're checking the same- ie. have a flywheel mark at 10, set RPM timing to 10 at 750, 1000 and 1100 rpm before checking with timing light at 1000 rpm. We want to make sure the module is using that 10 value, not an adjacent one.

Magnet Position is a one-time calibration to tell the CPU the actual offset. Once the timing gun says you're at 10 in this case, you can reset your RPM timing to whatever you want and it will be correct.

Ross - just for clarity for all of us, I had him move from the 10 degree setting you sent him to "TDC" because his ring gear does not have a "10" mark. Normally I wouldnt want to run at TDC, but he has a magneto on the other side doing most of the work so that allows the CPI to coast along during the magnet position setting. So IN THIS PARTICULAR INSTANCE, the "10" degree setting is not applicable for the mag position.
 
Ross - just for clarity for all of us, I had him move from the 10 degree setting you sent him to "TDC" because his ring gear does not have a "10" mark. Normally I wouldnt want to run at TDC, but he has a magneto on the other side doing most of the work so that allows the CPI to coast along during the magnet position setting. So IN THIS PARTICULAR INSTANCE, the "10" degree setting is not applicable for the mag position.

Yup, that's fine. As I said, you can use 0, 10 or 25 but you must remember to set your RPM timing values to whatever you choose to check initial timing at. Several people have not done this and became lost.

On single pickup installations, your Magnet Position should be around 88 to 92 if you've mounted the magnets correctly.
 
To follow up with our phone conversation, here is a step-by-step for you:

1. Using the top splitline of the case and the timing marks on the REAR of the ring gear, rotate the engine until it is at TDC ("0" degrees) on the compression stroke for #1 cylinder.

2. WITHOUT ROTATING THE ENGINE AGAIN, find a "convenient" place to view the ring gear with a timing light (You suggested somewhere near the starter).

3. Fabricate a pointer from wire or similar and affix pointer to case with the indicator somewhere within this "convenient field of view". Make sure the pointer is very close to, but does not touch the ring gear.
WARNING: Make sure this "convenient" position keeps all parts of your body and equipment well clear of the prop, ring gear, belt, alternator, etc. I grew up with strobe timing lights and for those unfamiliar, the view is "frozen" so the mind can trick you into forgetting stuff is rotating with significant speed. Its very, very easy to reach into an area that looks static, but in fact that prop blade is spinning at idle.

4. Again, without rotating the engine, mark the ring gear with tape and a sharpie so that the pointer and mark are in alignment as viewed from the timing light operator.

5. With the indicator secured, the ring gear marked and the two are in alignment, verify the engine has not turned by inspecting the factory timing marks at the top split line (still in alignment).

6. Make sure the timing light is hooked to the #1 cylinder CPI ignition lead (not the magneto).

7. Fire the engine on the CPI (magneto off). It will run, but it will be labored due to firing at TDC. Turn on the magneto (idle should improve significantly due to the 25 degree advance). Atain a normal idle at ~800 to 1000 RPM. (As Ross suggests, you dont want the idle moving high enough to do a timing shift. In your case, that would occur at the 1300 RPM mark).

8. With the engine running at normal idle, shoot the timing light at your fabricated pointer. Your tape/sharpie mark should be somewhere near that pointer, high or low. If its dead on, then you are done. Document the number displayed in the "Magnet Position" window in your logbook.

8a. If the mark is visible with the timing light but out of position high or low, then have a helper key the up or down arrow on the CPI box while in the Magnet Position window. Simply drive the mark into alignment with your pointer. When aligned, the resulting number in the Magnet Position window is "your" number. Document in the Logbook for future reference.

8b. If your tape/sharpie marks are not even visible anywhere on the ring gear with the timing light then there are a few probable causes (I've done ALL of these):
a). The timing light isnt working
b). The marks you made dont have the proper contrast for the ambient lighting
c). The timing light is hooked to the wrong spark plug lead
d). The CPI programming is off for the RPM or MP advance values (the guage window will show current advance - should be "0" in your particular case)

If all else fails, give me a call and we'll work it out.

OK, first of all, thank you and Ross for taking the time to help clarify the timing procedure. However, I'm still confused, so let me make some statements and you can verify if they are true or false. For the first set, assume I use the 0˚ we set on the RPM / IGN from 500 to 1200:

It does not matter where I locate the pointer or make a mark on the flywheel, as long as the pointer and the mark are aligned when the flywheel is set to TDC (aligned with case crack / #1 cyl at TDC.)

THUS

If I fabbed a pointer that aligned with the case crack, the mark on the flywheel will be made, coincidentally, at the TC (essentially 0˚) hash on the flywheel;

AND

When the engine is running and the strobe is aimed at the pointer, I will align the 0˚/TC mark with the pointer while in the MAG POS mode using the + / - buttons.

-----

For second set of statements, assume that the timing remains at the initial setting of 10˚ on the RPM / IGN from 500 to 1200:


If I fabbed a pointer that aligned with the case crack, the mark on the flywheel will be made at the 10˚ on the flywheel (guesstimating / interpolating between the etched 0˚ and 20˚ hashes;)

AND

When the engine is running and the strobe is aimed at the pointer, I will align the 10˚ mark with the pointer while in the MAG POS mode using the + / - buttons.

I *hope* I am understanding this procedure now. Please comment or correct.
 
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