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Mythical H2AD magneto drive oil feed

rjcthree

Well Known Member
I am in the process of removal of the D3000 dual magneto for aN electronic ignition system. There is forum discussion and some electronic ignition supplier discussion that the magneto drive gear has a oil feed port in the crankcase. I have had some reports from people with first hand knowledge of the respective engines that the port does not exist on the H2AD engines they are familiar with. I OH?d mine, and I simply don?t recall. I can say the Lycoming OH manual and oil galley diagram does not show a feed to the magneto drive gear bushing or cavity.

I?m asking this group for a couple things. First, have you personally seen an oil feed to the mag drive on an H2AD, or have you seen a case without it? Second, If you actually seen one, what direction did it come in from (top, bottom, back, etc)?

I have removed my mag drive gear, and using a direct inward look, I do not see an oil feed hole. I will look for a hole with a right angle reflector on a cheapo boroscope when I get back to the hanger. I may also low tech probe it with a chunk of copper wire.

I?d appreciate any insight anyone has to offer.
 
Interesting. My IO-360-A3B6D most definitely has an oil feed hole in the bore which supports the mag gear. Wonder why some engines have it and others not?

When I installed dual crank-triggered Lightspeed ignitions I turned a piece of round stock in a lathe which I attached to the mag cover plate which simulates the mag gear shaft and plugs the bore in the crankcase.
 
I have often wondered the same thing having also read the numerous threads that mention the oil pressure feed to this area. One thing I did notice is that all the threads that mention it are referring to the 0360 "duel mag" engines not the H2AD which is a different animal and has a different Mag drive setup .
I have a H2AD in my aircraft and two cores in my workshop. They all appear to be the same setup. Just a plain brass bush for the drive gear to run in with no oil gallery hole either in the wall of the bush or the crankcase housing the bush is inserted into(that I have been able to find anyway).
If that is the case and there is no oil pressure feed to the bush, how then is it lubricated and why then is there an "O"ring in the internal bore of the drive gear that the Mag coupling inserts into? (Figure # 2 in the pic). Interesting question indeed.

 
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Oring - alternate use

Airtractor8, Maybe the oring is a centering / clearance soak up between the parts? The radial fit between the mag and the case is not very tight, it?s got clearance. I think on assembly, the oring helps to improve concentricity of the mag drive to gear to bushing. It could also be commonality with something else, I don?t know if that same gear is used in the O-360-A3B6D, for instance.
 
Airtractor8, Maybe the oring is a centering / clearance soak up between the parts? The radial fit between the mag and the case is not very tight, it’s got clearance. I think on assembly, the oring helps to improve concentricity of the mag drive to gear to bushing.

Yep, it could be that.

It could also be commonality with something else, I don’t know if that same gear is used in the O-360-A3B6D, for instance.

No, its not used in any other engine as far as I know.

Here is a pic of the mag gear used in the 0360A3B6D Dual mag engine.

[url=https://postimg.cc/5Hn4rW6h][/URL]
 
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the magneto drive gear has a oil feed port in the crankcase. I have had some reports from people with first hand knowledge of the respective engines that the port does not exist on the H2AD engines they are familiar with.

The O-320-H2AD I had, had an oil port. When I removed the mag for an EI, I made a plug from a rather thick-walled aluminum tube that replaced the magneto shaft, blocked off the port, and was held in place by a mag hole cover. I have seen a kit which is the same sort of thing, machined for an o-ring. Thought I had a photo but can't find it.

I did not use any o-ring and my oil pressure was fine.
 
What I remember

I am running an O320H2AD in my -4 that I overhauled, but that was over 10 years ago. The H2 parts manual shows the bushing and a dowel pin, so the hole for the dowel pin may be what your seeing. Since the accessory case for the H2 is a part of the case halves, the lubrication path is somewhat different than all the other O320 and O360 Lyco's. Im actually keeping my eye out for a spare dual mag to build up for mine, so if you decide to part with it, I would be interested. Love my H2AD !
 
I have seen a kit which is the same sort of thing, machined for an o-ring. Thought I had a photo but can't find it.

Here ya go:
The Bendix Dualmag has two magnetos in one housing, which both share a common drive. They are expensive to service and are well known for having a short usable lifespan. The EFII Dual ignition is an ideal upgrade that will allow you to remove your Dualmag completely and get away from this costly and heavy device. Our Dualmag replacement systems include a special block plate that extends through the accessory case cover into the back of the engine case to properly block the oil passage that is revealed when you remove the Dualmag assembly. The Dualmag block plate is included at no extra charge when you purchase an EFII ignition kit.
https://www.flyefii.com/products/ignition-systems/

There used to be a picture. If you search for older versions of this website on the internet archive/wayback machine, you can probably find the picture
 
H2AD

Here is an image of the Dualmag snout:
Dualmag-gear-snout.gif

We have been told that some cases have an oil port and some don't.

Our Dualmag block plate has a dowel that extends into the case bore that is left open when the Dualmag is removed. There are two bore sizes found on these engines, 1" and .690". We have both sizes of block plate dowels available. The dowel that extends into the bore has an o-ring on it. If you have an oil passage, the o-ring will seal it. If you don't have an oil passage, the o-ring doesn't hurt anything.

Robert
EFII
 
The O-320-H2AD I had, had an oil port. When I removed the mag for an EI, I made a plug from a rather thick-walled aluminum tube that replaced the magneto shaft, blocked off the port, and was held in place by a mag hole cover. I have seen a kit which is the same sort of thing, machined for an o-ring. Thought I had a photo but can't find it.

I did not use any o-ring and my oil pressure was fine.

Robert (protek post above) makes a really nice plug with a captive O ring for this that bolts in place of the mag and can be used to mount your ignition coil. I had one on my -6, really nice.
 
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