Which Bendix mag for a single mag system

Hello fellow VAFers,

I am in the process of (re)building an IO-360. I'd like to start with a single EI and single mag. My thinking is that I'd go with a Bendix instead of a Slick, as I read that you can rebuild Bendix mags again and again, but Slicks cannot be rebuilt (or at least not for long).

Having said that, I'm looking for a recommendation for which Bendix mag to use for my O-360A1A. I'm hoping to find a used Bendix and either rebuild it myself, or have it rebuilt. I've searched the archives, and have not been able to find this information. Any help would be appreciated.

Thanks in advance,

David

I'm chasing a single bendix mag as well, but mine is for a single hole dual bendix mag accessory case. I would call a reputable mag shop, these 2 shops have been able to send me in the right direction...

http://www.aircraftmagnetoservice.net/

http://www.qualityaircraftaccessories.com/

Bendix Mag

crabandy said:

I'm chasing a single bendix mag as well, but mine is for a single hole dual bendix mag accessory case. I would call a reputable mag shop, these 2 shops have been able to send me in the right direction...

http://www.aircraftmagnetoservice.net/

http://www.qualityaircraftaccessories.com/

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Crabandy: Bendix SL4LN-21 mag, part number 10-50360-37 is the one I think you need for the dual mag single hole case. When fitted with the dual mag drive gear and impulse, it meshes with the mating gear at the proper depth and fills the pilot hole in the crank case. If you don't fill the pilot hole in the case, you have a large oil bleed hole that can cause a local low oil pressure area.

Mags

Most of the Lycoming parts catalogs list the proper magnetos for a given engine. I think you want a -30 Bendix. I prefer the Bendix mags to the slicks. At least some of the dash numbers relate to impulse lag angle. Some of the lag angles are no longer available.
I would strongly recommend a new impulse coupling. The new couplings have pins instead of rivets.The rivets have been know to come apart and that will probably trash you engine. This stuff is not cheap, the impulse is almost $400 and as far as I can determine is available only from Continental.

mannanj said:

Crabandy: Bendix SL4LN-21 mag, part number 10-50360-37 is the one I think you need for the dual mag single hole case. When fitted with the dual mag drive gear and impulse, it meshes with the mating gear at the proper depth and fills the pilot hole in the crank case. If you don't fill the pilot hole in the case, you have a large oil bleed hole that can cause a local low oil pressure area.

Click to expand...

Mannan,
Just to clarify, the bendix part # above works with no internal modification. I just need to purchase that # mag slide the impulse off my dual mag and slide it on the new mag. No special tools to remove/install impulse coupling?

Dual Mag

crabandy said:

Mannan,
Just to clarify, the bendix part # above works with no internal modification. I just need to purchase that # mag slide the impulse off my dual mag and slide it on the new mag. No special tools to remove/install impulse coupling?

Click to expand...

As far as I know. There's a couple of mag repair stations that can give you a better reading on this. One I talked to was Shaun at Eagle magneto service at New Smyrna Beach, Fl. Sorry I don't have his phone no. Handy. Try google, should find it.

I was going this direction until I decided to go complete redundant dual electronic ignition. I installed the EFII System.

Mag

I think some are misreading the original post. Single mag and single EI tells me that the engine was originally a conventional two mag setup. If this it correct the S4LN21 dash number is -30. This requires a spacer because the impulse coupling moves the gear forward. All two mag accessory cases that I have seen are set up for spacer with impulse, no spacer for non impulse.

Thanks for the info

Gentlemen,

Thanks for the inputs. I'll call the aforementioned magneto shops, but was hoping for a little education first. I purchased this engine from a guy that was running one Bendix and one Jeff Rose EI, and then later one Pmag and a Bendix mag , and finally just the Jeff Rose setup. As such, I expected I could run some variant of an S4LN Bendix magneto. However, looking at the Lycoming parts list for the O-360, it lists a D4LN or a D4RN, which I thought were dual mags. Can I get a part number off my accessory case to figure out which one it supports? Is there a Bendix cross reference chart somewhere that decodes all of this? I have seen a Slick engine/mag decoder, but nothing for Bendix yet. Have you guys had good luck rebuilding a used Bendix mag, or should I bite the bullet and buy an overhauled one from ACS or one of the aforementioned shops. Again, thanks for your education/advice.

David Dalton

Well

I don't have the number off my Bendix Mags, I will get it later today, but I bought my Bendix setup on Ebay and had them rebuilt. I think that is the good thing about Bendix, they are pretty easy to rebuild and unlike some of the Slick mags, can be done fairly cheaply. I might have an extra mag to sell also if your interested.

Randy
8A

Bendix mag

I believe the mag you will need is a BL-500514-1 mag. That is the impulse mag. If you order a factory mag you will get a new impulse and almost all new parts. I believe they are 720.00 and they will take any bendix or slick core back.

Jesse

My education continues

Thank you all for your posts. I will still be calling the shops several have suggested, but did a bit of research on my own first. Here are my findings, both for others to correct me in my mistakes, and to help others that come after me.

First off, here is a photo of my accessory case.


From my understanding, I can use this case to install a single dual mag ( and block off the other Mag port), or I can install 2 single mags or 1 mag and one EI. Obviously, I would need the appropriate drive gears and harnesses, but any of the above options should work with this case, correct?

Wanting to go with a single Bendix mag, I can then choose to go with an impulse mag or non-impulse mag. The issue is whether or not I want to use the mag for starting, in case the EI fails. In my case, if the EI is not working, I'm not going to launch, so I don't feel I need an impulse mag, unless I can find one at a very reasonable price.

I could go with a S4LN21 or with the 'newer' (1965) Bendix 1200 model which I understand yields improved performance over the original S4LN, although with the newer plugs that may be a wash.

Let me know if any of this is incorrect. Thanks for your help,

David

Mag

If you decide on a non impulse mag it is S4LN20. Part number is a dash 29 instead of the dash 30.Used non impulse seem to be a little harder to find than impulse right now.
I just finished overhauling one of my Bendix mags. Made a bunch of tools, bought a torque screwdriver 5-40 inch pounds and an arbor press. I used to work on these mags many years ago but had never pulled the inner bearing races. The tools are for removing and installing the bearing races plus a test stand for testing the mags driven with an electric drill. It makes spark.