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  #1  
Old 01-13-2018, 12:08 PM
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stringfellow stringfellow is offline
 
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Default Omitting/deleting accessory case gears

I'm building an IO-540 which I will be using EFII on. I'm at the stage of installing and indexing the idler gears (done.) It has been suggested that I leave out the magneto drive gears during reassembly because they won't be used by the electronic ignition (EFII is timed by crank sensor, powered by battery.)

Any concerns with this? Unless I sell the engine, it's doubtful the mag drives would ever be used. If they ARE installed, but drive no mags, am I wrong in thinking that's even more risky?

The next question is: I'd like to use the vac drive to power a backup alternator like this (8A is not enough for EFII fuel pumps.) Do I use the old vac pump adapter too? To be honest, all my parts are down at the shop I'm currently using, and I'm trying to determine if the pump adapter with its oil seal is required for using the alternator. I imagine a quick call to B&C would help but it's the weekend.



I do recall a conversation here a while back about how using that can create a massive internal oil leak, but I don't remember exactly how.

So basically, I need a little guidance on deleting unnecessary gears for EFII, and how to use the vac/accessory drive for an alternator.

Thanks!
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  #2  
Old 01-13-2018, 12:36 PM
bcondrey bcondrey is offline
 
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You do use the standard vacuum pump drive for those alternators. Keep in mind that if this is going on an RV-10 and if you use that alternator in combination with the B&C angled oil filter adapter, you’ll need to also get the 3/4” spacer kit for the alternator for clearance.
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  #3  
Old 01-13-2018, 01:28 PM
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Toobuilder Toobuilder is offline
 
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You absolutely must remove the mag drive gears because without the magneto in place they are only supported on one side (the bearings pressed into the case). Depending on how tight the fit is will determine how long it takes for the gears to back out, chew up the mag cover, destroy the teeth and egg out the holes in the case. But it WILL happen.

As for the masive internal oil leak through the vac pump adapter, that is because the shaft is pressure lubricated through the accessory case. Remove the shaft, and you have an 1/8 inch oil port pumping into the empty void where the shaft used to be. You can run the adapter without the shaft, but you must use a "cover" gasket (item #7 above), which blocks the oil passage.
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Last edited by Toobuilder : 01-13-2018 at 01:30 PM.
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Old 01-13-2018, 01:50 PM
bcondrey bcondrey is offline
 
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Toolbuilder's comments regarding the vacuum pump drive are correct IF you aren't going to use it. If you are using a vacuum pad drive alternator however, you must keep the vacuum pump pad and drive in tact. Think of those alternators as a drop in to replace an unneeded and removed vacuum pump.
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  #5  
Old 01-13-2018, 06:30 PM
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Toobuilder Toobuilder is offline
 
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I put my 540 back together with the idea that the vac drive was not going to be used, so I cleaned out a bunch of stuff back there. I removed the tach drive, the fuel pump pushrod, the magneto drives and bearings, one of the accessory driven gears and shaft, and went on to swap the driven gear with the fuel pump lobe with the one from the other side (the "non lobed" one).

And yes, the driven gear shaft was replaced with a cover plate, as it is also pressure lubricated.
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  #6  
Old 01-13-2018, 06:56 PM
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N941WR N941WR is online now
 
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It can depend on the engine.

I know of one O-360 that was assembled without the tach drive gear and it didn't end well for that engine.

It turned out that an oil squirter was aimed at that shaft and without it in place the oil went right out the breather tube.

He had to overhaul his engine with all of four hours on it. The only change he made when it put it back together was to include the tach drive.

Also, there are a number of planes flying with Lightspeed ignitions where the mag was removed, the hole covered, and flown for many hours without any issues.
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  #7  
Old 01-13-2018, 07:51 PM
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Bill, are you suggesting a 540 has been operated with the mag removed, but the drive assembly was still in place?
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  #8  
Old 01-14-2018, 01:54 AM
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stringfellow stringfellow is offline
 
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Quote:
Originally Posted by N941WR View Post
It can depend on the engine.

I know of one O-360 that was assembled without the tach drive gear and it didn't end well for that engine.
Interesting. I had intended to leave the tach drive out on my 540. It's just a tee that slots into the end of camshaft. There is no gear as best I can remember.

I removed many studs from my accessory case housing with the intent to just bolt on cover plates.
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  #9  
Old 01-14-2018, 05:42 AM
vic syracuse vic syracuse is offline
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Quote:
Originally Posted by Toobuilder View Post
You absolutely must remove the mag drive gears because without the magneto in place they are only supported on one side (the bearings pressed into the case). Depending on how tight the fit is will determine how long it takes for the gears to back out, chew up the mag cover, destroy the teeth and egg out the holes in the case. But it WILL happen.

As for the masive internal oil leak through the vac pump adapter, that is because the shaft is pressure lubricated through the accessory case. Remove the shaft, and you have an 1/8 inch oil port pumping into the empty void where the shaft used to be. You can run the adapter without the shaft, but you must use a "cover" gasket (item #7 above), which blocks the oil passage.
I'm not so sure about what is being referenced here. There are bearings for the magneto drives that are press fitted into the engine case. Those should be left out. The larger magneto drive gears can stay in the engine. It is common practice to remove a mag and place a cover on the hole when using an electronic engine. The drive gear is physically attached to the the magneto. the larger drive gears left behind in the accessory case aren't going anywhere.

Vic
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  #10  
Old 01-14-2018, 06:58 AM
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maniago maniago is offline
 
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This seems more like a question worth asking on the Lycoming yahoo group. If you can get Mahlon to ans you got the recognized expert.

I dunno, but you might have a diff between 540s and 360 accessory cases, as I've not ever heard of any need or recommendations for removals for the 360 with EI, so carefully qualify any answer you get.
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