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Sent my Slick Mag for 500h inspection, came back some days ago. Will put it back next week. Also ordered a Maggie Harness cables, hopefully they will be ready to ship next coming weeks. I noticed that the I don't have standard Adel clamps on one side of the engine. There is some similar clamp, that they do really put pressure/force on the cables. More than I think is healthy for the cables. Since I changed the Slick Mag (Left side) and it behaves exactly the same as the other, I'm starting to suspect that the harness is bad. Yesterday I got it running smoothly at 28" 2300rpm with 10.1g/h.

Hi all, I’ve got a bad wire, and figure it makes sense to replace both harnesses as they’re the same age. It seems like the Maggie harness is popular, but not clear why it over the Slick. Are Maggie priced better, better quality, or both? Also can’t seem to find any Maggie pricing. I’d call but they’re close til Monday. What they go for compared to Slick? It’s an ‘87 J, IO-360 A3B6 (one slick mag and one Surefly, but both use the slick harness). Thanks, and happy Saturday all! (Ps, I have searched and read the threads I could find, just no answers for these questions).

I just installed a SureFly on my 1970 F, left mag, replacing the Shower of Sparks magneto. So far have been happy with it, but only a few hours flown. Starts nearly instantly cold - almost 'first blade'. Don't know about hot starts yet. Right mag was overhauled. Maggie harnesses installed (highly recommend them). No radio noise from the ignition. Hoping for a long life on this unit....

I had the “A” version on my F and it was flawless for ~500 hours that i put on it. I’ll put one on my 252 when the mags are due for inspection. My #2 alternator whines just a little now, there’s always something. Curious, what harness are you using? Did you get a new Maggie one for the SF? My local shop tried to put one on their SR20 and couldn’t get it to work at all with their old harness even though it tested fine and worked perfectly with the mag. Eventually they got a new harness and it worked.

I have a surefly and replaced both wiring harnesses with new Maggie harnesses and tempest fine wire plugs. The surefly gets me .5 less fuel for same performance and I can go about 70 degrees lop before roughness. I’m at .2 spread on my gami injectors. The gami sweep at 65% unfortunately doesn’t magnify your spread as much as higher power setting will. And if you start at poh book values for 65% they were for ROP flying so as you sweep for your gami test the power will be less than 65%. Mike Busch talks about the big mixture pull which he does at wide open throttle so he is sweeping through peak at full power but is rapidly doing it and does not even know what LOP setting he is at because he doesn’t measure his lop he measures CHT values. He states from engine detonation testing in Ada OK that at the most destructive air fuel setting at full power they do not see detonation until the cht have climbed through 420 degrees so he knows even though he is leaning through the destructive zone because his cht’s are all below 380 he knows there is not detonation. Now if you go too slowly you will see your cht’s start rapidly rising but its not instantaneous and you do have seconds to get through it. My point is since my JPI records fuel flow and egt I did my gami sweep at 75% power and did it quickly then went back and downloaded the data to savvy aviation and used their gami spread chart to show that at 75% power it magnified my gami spread to greater than .5 so I was eligible for gami injectors which got me down to .2 my limitation is either cht 380 in the summer or 1585 tit which I hit in the winter at 31” 2300rpm 11.5 ff gets me 75% power lop but I routinely fly 10.2 which keeps my tit below 1550. I would not be so worried about the red box as much as what the Redbox will do to your cht’s which is push them rapidly past 380 and above 400 I would really be worried that detonation is about to. begin. It’s your cht’s that dictate how close you can run to the Redbox. If you want a good wiring harness spark plug test on your next run up go to 1800rpm then lean until you get the rpm’s to drop to 1700 THEN do a left and right mag check. My mag will drop 150 more rpm but will still run with all spark plugs firing my surefly only drops by 75 rpm a testament to the hotter longer spark. If you have a weak spark plug or wire or partial fouled plug you will feel it in roughness or egt dropping (or rising higher if you are so lop that the flame front so slow it’s still burning as the exhaust valve opens up cooking your egt prob) point is the offending wire / plug will be an outliner to the other plugs wires when you go back and look at your engine data to identify your weak point.

Has anyone installed Maggie ignition harnesses on their Bravo? I’m ordering Maggie harnesses and they sent me a drawing showing plug wire lengths that don’t appear to match what I have on my engine. I did a rough measure of my top plug wires in place and for instance, the left mag #1 wire to cylinder #1 top is about 51” as compared to 71” on the Maggie drawing. I’m hoping to take the lazy way out and not have to disturb the installed wires to measure them accurately. Has anyone measured the length of the wires on your Slick harnesses? EDIT: Or better yet, has anyone already ordered and installed the Maggie harnesses and will let me duplicate your order? Here’s the drawing: TIO-540-AF1B Print.pdf Thanks! Junkman

Hello all! I’m about to install Surefly Magneto and have read great reviews about the Maggie Ignition Harness but the link on most forum posts is no longer valid. Did the website change or did the company go belly up? I plan to try to call whatever number I can find tomorrow. Thanks!

Best mag was the 662 slick back in the day , the psi mag is a great mag matched with tempest iridium and a Maggie harness as you want elbows to reduce strain on the lead assy . I designed the color harness for slick back in the day , they came to me and asked if I wanted to work for them , I was just 27 years old and traveled the world. Sad what happened to a great product GB

When I had surefly installed on my Acclaim we went with the Maggie harness, I haven’t seen any discernible difference between either one at high altitude but only went to 18,000’ so not real high.

Sort-of Necro-Thread Post: Adding a SureFly to my Rajay equipped M20F. SureFly said I should maybe go with Champion for higher altitude flying. OK - Reach out to the person at Champion recommended, and get nothing back. So, I think I want to go with the Maggie harness. Anyone have any feedback with regards to the Maggie harness and high altitude? I don't plan on flying in the flight levels, but would like to know if more than 12k feet is likely to be a problem or not....

ArtCraft Paint in Santa Maria CA painted my Maggie. We used the blue color plus Pismo Beach sand. It has held up very well over the last 12 years!

I ordered from New Horizons / Maggie when I was installing a Surefly. They just needed info for my engine, mag harness cap type, and airframe. I didn't send them my old harness and the new one fit perfectly.

Maggie Harness is good should you decide to go that route. Although the lead time can be long. you will need to send your old harness. Are you sure it is the harness ? is it in that bad a shape ? shield in bad shape ?? And what do you mean by shutting both off and voila ? the engine is still running ??

+1 for Maggie Ignition Systems. Also check that you don't have one or more plugs out of resistance spec, i.e., >5k Ohms.. https://www.maggieignitionsystems.com/

Maggie's Harness.

I struggled with hot starts when I first got my F model. Mags were due for overhaul and the ignition harnesses were ratty; that said, cold starts were fine and my LOP mag checks per Savvy did not show any abnormalities so I was initially hesitant to blame the equipment and figured I was doing something wrong. Eventually did the mag overhaul and put in a set of Maggie harnesses when the plane was next down for maintenance, and everything got better. I spent a while agonizing over technique, but now agree with others that you should carefully consider an ignition problem rather than something you’re doing wrong in the cockpit. Just to add another technique you could try: I tend to shut down the engine between 1100-1200rpm as others have mentioned. When ready to start, don’t touch anything; if you feel compelled to do something, advance the throttle another eighth inch but leave the mixture and pump alone. Then start cranking. After a very short shutdown to refuel, it should catch pretty quickly without other intervention. If a couple seconds have gone by with no firing (common with a 15-60min hot start), I will slowly advance the mixture until it catches, while continuing to crank. When first trying this, figure on 2-3 real seconds of easing the mixture forward. It will start to catch a bit, and then as you go another half inch forward, it’ll actually start and run smooth (by hot start standards anyway). Over time, I got a knack for what mixture position runs smooth with this method, so now I advance more directly to that spot rather than a slow push through the stumbling-because-still-too-lean region. This is also the spot I push the mixture to during any other start attempt (cold starts or if it fires right up during the do-nothing phase of hot starting). I’ve flown just over 60hrs in the last 30 days (most if it concentrated in two busy weeks with multiple legs per day), mostly in 80-90deg heat, so did quite a few hot starts and didn’t have any tricky starts using the above technique. It’s usually started in under 5sec of total cranking time (either fires right off or it’s time to give it the appropriate lean mix), so not particularly hard on the starter. Sent from my iPhone using Tapatalk

Has anybody that has a surefly electronic ignition flown it in the flight levels? I just got off the phone with Maggie harnesses and their tech guy warned me that surefly has been having arcing problems at altitude because even though the Sim will not arc like a an unpressurized mag will they have seen arcing in the cap where the leads are and thus need to pressurize the cap to keep that from happening. I talked to jim Baker that doesn’t do mooneys but does do cirruses and he confimed that you have to get better insulation in the cap or pressurize it where the lead wires enter or you will get arcing in the flight levels. So anybody with a surefly installed, have you tested it up in the flight levels yet? Have you modified the cap to keep this from happening?

Reviving this thread to see if there's been any updates? I installed a Surefly with a Maggie harness a year ago at annual and have been up to FL's from time to time and have not experienced any misfires. My shop didn't offer to pressurize the cap and just removed the upper deck pressure line and the T that went to the previous mag it replaced. But I was talking to a fellow M20K pilot the other day who mentioned about drilling a hole in the cap for the pressure line...I don't recall coming across the idea of pressurizing the cap previously when I was learning about installing a Surefly. @kortopates did you pressurize your cap and do you or Savvy typically recommend this?

Friday, I was in Fairhope, Al AOG with a rough running engine and no EGT on 1 or 4. Continental had one of their guys take a look but, only had time for a quick fix so I posted looking for another A&P option just in case but, moving the plugs around (not cleaning or anything, just moving) seemed to resolve the issue so, I deleted the post, to the disappointment of some. I flew a little over 5 hours home and everything seemed fine until this morning when I went to the airport to fly to Dallas. Fired it up and same thing, very rough and no EGT on 1 or 4 so I taxied over to Dugosh. We pulled and tested the plugs and they were all good, which I expected since the problem was on the same cylinders and the plugs have only been in for about 10 - 15 hours. Next I got the high voltage lead tester and tested the plug wires, all good, again expected since they're both new Maggie's harnesses replaced about 10 hours ago. Borescoped the cylinders and valves were moving fine and looked good, although 4 had fairly heavy lead deposits and and 1 had them less so. We speculated that maybe the lead was falling into the plugs and causing them to not fire consistently so I cleaned up the plugs, reinstalled and ran the engine. Initially, it fired up and sounded great. I planned to taxi into a less trafficked area and do a full power max lean run up to burn some of the lead off the cylinders however, as soon as I started to taxi, it started running rough again and the EGT on 1 and 4 dropped off. At this point, we figure it's got to be the magnetos so I go ahead and pull the right one off and open it up. Sure enough, the points and rotor have pretty good carbon buildup and there's oil in the mag. Pulled the left and it's the same except to a lessor extent. I was going to replace the worn parts except that the repair kit for the right side mag is unavailable anywhere so I instead ordered a couple of overhaul exchange mags and we're going to just swap them out. If you've never seen the guts of a magneto, here they are. This is the right mag, the worse of the two, and you can see the buildup. What you can't see is that when you open the points, it had lots of peaks and valleys and was also pretty black. Anyway, now that we've found the actual cause and it was information I thought might be useful to someone, I thought I'd share the results. "We moved plugs and it ran ok" didn't seem all that useful to me, which is why I deleted the original post. As it turns out, it was just coincidence that it "solved" the problem anyway. Once again, the airplane decided to really break down at home, it's done this to me several times now. First with the starter, then the alternator while we were en route to home, then the stuck valve that bent a push rod at home and now the magnetos finally not working for good. I consider myself very lucky that these things haven't happened far from home and I've always been able to just pull the plane into Dugosh when things do break down. I hope that luck continues, I'm grateful for it. Sure the breakdowns suck but, I'm running 80+ year old technology in a 61 year old airplane so, those are going to happen. If they keep happening at home, I've got nothing to complain about. ***EDIT TO ADD*** The plane had gotten a little harder to start in recent months, not enough that it concerned me but, enough that I noticed it. I found that a couple of extra pumps of the throttle with the fuel pump on more or less solved that though, which is why I wasn't too worried about it. Lesson learned though, engines talk to you, next time something changes I'll dig into it more thoroughly.

Decided on putting in the SureFly and getting rid of the left MAG and Shower of Sparks, A&P asked me if I wanted it configured standard or to allow for advanced timing at higher altitudes.....I've heard stories of issues with the advance timing and a few people on this forum, a few years ago recommended against it.....looking for more recent information incase they had an issue previously but have worked the bugs out. Yes, got new harnesses made (Maggie). I appreciate your time.

The Kelly PN is 10-821414-6R. FWIW, the outer sheathing on the Kelly harnesses seems to be a bit too soft and some people (incl. me) have seen the outer sheath wear off under abrasion. It is otherwise a good harness, and if you are able to add some additional protection in pass-throughs and around other abrasion opportunities it'd probably be fine. I'm still running mine and other than looking like crap in a few places it functions fine. +1 that you can also get one from Maggie Ignition: https://www.maggieignitionsystems.com/ They make good stuff.

Just order a harness from Maggie, they will get you the right one.

I have isolated the static noise on both my radios to the left Magneto i have a surefly on the right and when i run on only the surefly the noise is gone from both radios. ATC says my transmissions are clear on both radios so this is only effecting receiving. Last oil change i swapped all sparkplugs that were on the surefly with the ones on the magneto and the noise is still only with the magneto side. Is there a way short of taking the magneto for an IRAN to see what is causing the noise? This noise has appeared in the last 2 months. I had my magneto IRAN in oct 2021 on my first annual as it was at it’s 500 hour point. It performed flawlessly in the 11 months i had the plane before i IRAN it only because it was at its time for a check. Now less than 230 hours on it and it seems to be the source unless there is something else i can test or check as i do not want to do another IRAN this early and it would be even a bigger bummer if the IRAN did not fix it. I installed new maggie harnesses on both the mag and the surefly in that first annual so i would not think it would be the electrical components but yet with a mag check in flight the noise stopped so it’s definitely one of the three or something else I’m overlooking that maybe the mooney hive might know to check?

I talked to christine at maggie and to be clear the screws are installed by your A&P not at maggie which makes since as they do not know if the harness is going on a surefly or magneto. This is the first case they have heard of screws coming loose on the cap. Maybe my engine is producing more vibration than normal or the screws on the magneto were not tighten properly as my screws on the surefly are still tight. I still think maggie harness is a great product and it has worked flawlessly including when this cap came loose from the magneto the magneto still was working and if it was not for the increase noise in the radio i would not even known there was a problem.

Hello William! Christine from Maggie Ignition Systems here! We pride ourselves on customer satisfaction and safety and would like to further discuss with issue with you ASAP in depth. Please call me at 310-648-1593 so that I and the shop foreman can discuss with you.