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Ditch the Slick?

Doug Rohrer

Well Known Member
I bought an O-320 engine that came with two Slick mags that need rebuilding before running. The model numbers are 4370 and 4347. I understand the 4347 is a retard timing mag that should have a Slick Start device added to make it reliable. This sounds expensive on top of a mag rebuild.

I see two options:

1) Swap the 4347 for an impulse coupled mag. If I do this, which model should I look for? I see mags for sale all the time on this board.
2) Replace the 4347 with a PMAG. If I do this, is there any reason I could not run the 4370 on the right side and the PMAG on the left?

Thanks.
 
+1 for that :D

May take a little longer to install but well worth it. Better starting hot and cold, more economical, NGK car plugs @ $7 a piece. What's not to like ?
 
Another plus to that! Besides the added performance and reliability, you will save about a gallon per hour.

Bob
 
slick replace

aaand - I have a brand new PMag I'll sell. Got 2 in a deal, only using one. -114, v.40, includes plug wires and late- style clamps. You'll need your drive gear, adapters for the plugs, plugs, 3 amp breaker/ switch, and a 'T' for the MP line. Looking for $1300, plus ship.

Seriously: dump that Slick, get something that will start.
 
Whenever this subject comes up, the pro electronic ignition people claim better performance, reliability and fuel savings.
I can believe advanced timing allows running further lean of peak than fixed timing of a mag. But lean of peak is very similar to lower power settings in my experience.
Better performance? The CAFE Foundation found that mags produced more power than electronic ignition.
Reliability? Many tens of thousands of airplanes have operated reliably with mags and electronic ignition has had its share of problems over the years.
Electronic ignition may be right for you, but in my opinion the advantage of electronic ignition is being overstated in the rush to modernize the venerable and extremely reliable magneto equipped Lycoming and its clones.
 
I wish you guys would stop holding back and tell me what you really think! I used the very helpful search tool here and read many posts about mags and EI. Given my current situation, I was leaning towards the compromise position of one each, which would allow for going all EI at a later date. Many have done this and seem happy with their decision. The PMAG solution sidesteps any issues with modifications to my ancient 122 T flywheel and concerns about losing ship's power, so I was leaning that way now that it appears that birthing issues have been resolved.

Thanks for the responses. Now tell me what you think about primer... :D!
 
To answer the OP's question #2, one mag and one PMag is a great combination and is, in the words of one very respected member of our community (not me), his recommended approach to EI. I think he knows who he is and he can chime in if he wants.

If you want to go that way, and want the best combo, my opinion is one Bendix mag and one PMag. Having said that, I have two PMags and very happy so far. The engine starts smooth as butter, runs smoothly at low RPMs, and the spark plugs run me less than $3.00 each. Plus PMags are dirt simple to install and time. Others have other opinions...
 
Given my current situation, I was leaning towards the compromise position of one each, which would allow for going all EI at a later date. Many have done this and seem happy with their decision. :D!

If you take a transitional approach like the above, then just have one Slick rebuilt without the impulse coupling. That's the cheapest way out I think.
 
Yes, it's like the primer wars, and we can all spout claims until the cows come home. Personally, I like a bit if redundancy, everywhere I can. Perhaps it comes from my time in the technology world, and some of it is from aviation experience. I'm a firm believer in one mag and one electronic ignition, just as I am a firm believer in an EFIS backup from a different manufacturer. You just never know when you might hit the same bug, or have the same failure.

And since there are claims that a mag is better or an electronic ignition is better, I figure I have the best of both worlds. :)

I am not saying you are wrong if you go with 2 of each. It's just my practice and my opinion. :)

Vic
 
Mags?

I?m with Vic. Most of the benefits and still retain 1 mag. I?m going to start with 1 impulse Slick and the Electroair system on the other side. If I was going to cross a ocean would want 2 Bendix mags.

Don Broussard
RV9 Slow Rebuild in Progress
57 Pacer
 
I?m with Vic. Most of the benefits and still retain 1 mag. I?m going to start with 1 impulse Slick and the Electroair system on the other side. If I was going to cross a ocean would want 2 Bendix mags.

Don Broussard
RV9 Slow Rebuild in Progress
57 Pacer

what about treating every flight as if you were crossing the ocean, except for the life raft?
 
Like Vic, I enjoy having a toe in both pools... Being concerned about being able to get an engine started when miles and miles from nowhere, after I've left the master "on" and drained the battery, led me to stick with one 4371 impulse coupled Slick mag and one P-Mag. This way I can always hand-prop the airplane, even with zero charge in the battery.
 
what about treating every flight as if you were crossing the ocean, except for the life raft?

The risk/serviceability/easy starting/gas mileage equation is different for everyone. My experience tells me the failure rate of a well maintained Slick with impulse is more than acceptable for the kind of flying I do. I also want the hot spark and variable timing and the electronics have evolved to the point where I can comfortably go with 1 for the kind of flying I do. Being able to limp along for 20-30 min to a suitable airport on 1 system is acceptable to me with what I?ve chosen.

Don Broussard
RV9 Slow Rebuild in Progress
57 Pacer
 
Whenever this subject comes up, the pro electronic ignition people claim better performance, reliability and fuel savings.
I can believe advanced timing allows running further lean of peak than fixed timing of a mag. But lean of peak is very similar to lower power settings in my experience.
Better performance? The CAFE Foundation found that mags produced more power than electronic ignition.
Reliability? Many tens of thousands of airplanes have operated reliably with mags and electronic ignition has had its share of problems over the years.
Electronic ignition may be right for you, but in my opinion the advantage of electronic ignition is being overstated in the rush to modernize the venerable and extremely reliable magneto equipped Lycoming and its clones.

I respect people making their own choice and certainly respect the risk involved with EI. However, using incorrect data to justify your position doesn't make any sense. An ignition advance, retarded from optimum, does reduce power at most fuel flows and that is a fact substantiated over and over, though the Lycoming may be less sensitive to it than other engine designs, due to it's very low RPM limit. 25* is not the optimum advance for a Lycoming engine. It's certainly warranted at certain power settings to reduce detonation potential, but it is not optimum.

I have no idea what CAFE did, but I and others have watched RPM (FP prop) and speed increase just by increasing ignition advance in cruise at a constant fuel flow. For me that was both at Peak and LOP.

Larry
 
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Whenever this subject comes up, the pro electronic ignition people claim better performance, reliability and fuel savings.
I can believe advanced timing allows running further lean of peak than fixed timing of a mag. But lean of peak is very similar to lower power settings in my experience.
Better performance? The CAFE Foundation found that mags produced more power than electronic ignition.
Reliability? ...
If you stay low and do not allow the electronic ignition (any EI) advance, then they will be very close, if not the same.

When you are in cruise, up high and the EI can advance, that is where your savings is.

The theory behind that was explained in the talk I gave last week. Here is the recording of that WebEx.

Reliability is always a good question and I honestly don't know if the EI, any EI, is more or less reliable than a Slick. I do know the EMAG guys, Ross, and the rest continue to improve their products and they all pretty much to the point where I suspect their reliability exceeds that of a mag. (Just a couple of weeks ago I seem to recall reading a post about someone with a bad Slick.)

In my experience, many of the EI problems have to do with installation and not the ignitions themselves.

Good luck making up your mind.
 
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Me too

Doug, I think you’ve got a lot of people’s opinions that sound a lot a like. As we have discussed before. I also agree for me one impulse mag and one electric is the way to go. I use a impulse slick on the left for the bottom plugs and a Lightspeed Plasma II with a mini sensor behind the flywheel. I started with a halls effect sensor, it had a couple problems, switched to the mini - no more problems. I am very happy with this setup. If I was doing it today I’d do the same or possibly try one impulse mag and one pmag. I believe either one of these setups would be the best option for me. Build on and get r done! :)
 
The CAFE Foundation published 3 studies on electronic ignition performance compared to magnetos. Search "CAFE Foundation and electronic ignition" and links to the publications readily come up. At all 3 altitudes, including 15000 feet, the dual mags were faster than the dual electronic ignition, even with ignition advance of the electronic ignition. Read the research and decide for yourself.
 
Different EI?s?

In the interest of what Vic said about different manufacturers, what about 2 different EI systems? Say a Plasma III and a Pmag?
Just curious if anyone has such a setup and how well the two separate systems play with each other.
 
I have been running an Electroair and Pmag for a couple of years now, no issues, runs great etc.
 
I bought an O-320 engine that came with two Slick mags that need rebuilding before running. The model numbers are 4370 and 4347. I understand the 4347 is a retard timing mag that should have a Slick Start device added to make it reliable. This sounds expensive on top of a mag rebuild.

I see two options:

1) Swap the 4347 for an impulse coupled mag. If I do this, which model should I look for? I see mags for sale all the time on this board.
2) Replace the 4347 with a PMAG. If I do this, is there any reason I could not run the 4370 on the right side and the PMAG on the left?

Thanks.

Retaining one mag with a complementary EI is no issue if it gives you piece of mind. With the ability to keep the engine running in the unlikely event of the loss of the alternator and battery, then P-mags only market differentiator (the on board alternator) evaporates. Now you can compare pure "function" across all systems. You will need one with a curve broad enough to retard below data plate values for detonation margin as well as advance appropriately for best power to keep your CHT in check, AND provide the additional bump when you want to run LOP. keep in mind the overall advance curve will need to be even more broad to be able to overcome the fixed timing of the magneto. While you are at it you will also want to be able to adjust your start retard to gurantee no kickbacks regardless of your compression or prop weight.

There is only one system I know of that has all of this functionality built in, and it happens to be the lightest and least expensive on the market. Its the SDS CPI. Give it a look.
 
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