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Converting a new O-320-D1A to FP

BruceP

Well Known Member
I have a new O-320-D1A hanging on my plane and I'm at the point where I need to convert it to a fixed pitch prop. I am told that it does not come cofigured for either FP or CS, that you must make the appropriate conversion yourself. I have the directions from Lycoming but I thought I would ask this group for any advice, pitfalls, etc. about doing that conversion. I am hoping this is all straight forward but I'm nervous about how to even get the front plug out and start the process! Thanks for any advice you may have.
 
Are you planning on leaving the prop governor drive and plumbing installed on the engine? There is a much easier way to do the conversion, that what Lycoming tells you, if you are. You can simply install a governor drive pad cover plate that has a galley machined in it to vent the oil from the nose of the crankshaft back to the crankcase through the prop plumbing and governor drive pad. No plugs to pierce or remove and reinstall this way and the conversion back to CS is easy as all that is necessary is to remove the cover plate. If you are going to remove the governor drive and plumbing then you have to remove the front crankshaft plug, pierce the rear one, and install a new front plug. The problem with that approach is that you must remove and install a new rear plug if you ever want to go CS. It is doable without taking the engine apart but it is a real PIA.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
I just did this last month with my new engine from Vans (drop shipped from Lycoming). I called Vans to see if I really needed to removed the front plug, pierce the inner one and replace the front plug with a new one since the governor drive pad cover and plumbing were in place. The folks at Vans said I would need to remove the front plug, pierce or remove the inner plug and replace the front plug with a new one.

I called Lycoming and after they looked up my engine info, they told me the same thing that Vans said.

I had been told by a few folks that I believe know what they are talking about that it would be okay if I just left all as it was, but I chose to do what Vans and Lycoming said I needed to do.

So, I pierced the front plug with a screwdriver and popped it out. I decided to remove the inner plug altogether since it is just baggage at this point. I pierced the inner plug and could not get it to budge, so a fellow builder lent me his slide hammer with a big screw mounted on the end. I threaded that into one of the holes I had pierced in the inner plug and with a few minor taps with the slider hammer, the plug came loose easily. It took some finagling to get the plug out past the cross tube.

To install the new front plug, I went with Lycoming's suggestion to use a ball peen hammer as the install interface (they also will rent you a proper tool). I set the plug into the crank. It is shaped like a giant steel contact lens. The convex profile to the forward. A few taps with an 8# hammer, the plug dimpled and set in. We shall see if it leaks pretty soon! I hope to have first engine start within an week or two. Made me really nervous to be operating on a brand new engine! I would be less comfortable if I ignored both Vans' and Lycoming's advice though.

I suggest calling them both to see what they say. After bargaining with them, I could not get them to budge on their stances.
 
do you have additional specs on the engine? why don't we just swap engines? I want to go CS and I've got the -E2D, 650hrsTT

edit: oh it's new, you probably like it more than i do :\
 
Do what Mahlon suggests, much easier and less risk that punching things out. Also allows easy re-conversion to CS in the future if required.

Pete
 
DSC01830.jpg


Mahlon,
The engine came plumbed with the line from the front of the case to the back as you see in the photo. So there is a different cover plate for the governor than the one that came with the engine? If so, do you know what the part number is to do the conversion you mentioned?
 
Take a picture of the installed prop gov cover plate, from the rear, and I can tell if it needs to be replaced or not to be used for FP and will advise.
Good Luck
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
The raised portion on the lower left corner of the plate indicates you have a machined slot on the other side of the plate. And that slot is what is allowing any oil pressure from the nose area of the crankshaft to be vented back though the prop governor plumbing, to the drive pad and then to the crankcase through that slot in the cover plate. So no oil pressure can build up in the nose of the crankshaft and blow the front plug out of the shaft because that plate, slot and the plumbing takes the place of a hole in the rear crankshaft plug and allows any oil pressure to be vented. So you should be all set, as is, for FP operation.
There are many cover plates, out there, that don?t have the slot and there are also some out there that do. The key to success is to have one that has the slot.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
The Crankshaft front plug

I received a message that told me the front plug in the crackshaft is to be removed with this new adapter cover plate. Any thoughts on that? I'm struggling to see how that can work.

Bob Axsom
 
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Sounds like an excellent way to keep the whole front of the plane well lubed and corrosion-protected... for a short while anyway.

Methinks the correct solution is to have both crank plugs in place with the oil line in place and the special slotted cover plate over the back of the governor drive adapter. The normal oiling of the front crank bearing via the crankcase oil galleries and the oil crossover tube inside the hollow portion of the crank will still fill the hollow end with oil at somewhere near the engine's oil pressure, and it needs to drain back thru the line and into the governor drive adapter and then back down into the sump via the slotted cover plate. At least that's my understanding of how it all works.
 
Plugs

For fixed pitch prop-front plug in place-hole in rear plug OR solid rear plug with governor line returning oil to governor pad cover. The external line with solid rear plug allows switching back and forth between fixed pitch and constant speed with much less work.


For constant speed- solid rear plug NO front plug.
 
That was my conclusion as well

The source is highly respected so I tried to mentally make it work. I must have misinterpreted the input - my fault in word mismanagement I'm sure - thanks for the reality nudge. I'm sure in retrospect the intent was "you have to take the forward plug out to go back to C/S operation" - I need more sleep. I have the special cover and forward plug on order.

Bob Axsom
 
Engine Conversion

So it's been about 5 years since this thread was active. Since then someone must have tried it and can report their success (or not). I have my engine installed, O-320D1A, setup for CS operation and plan to use a FP. I like having the ability to convert back someday without major surgery.

So does this work? What is the part number for this special cover?

As an alternate, if I were to follow the Lycoming SB and pierce the rear plug, what can I expect to invest time-wise? I'm certain that removing the engine will be a first step.

Thanks to all!
Ken
RV-9A (Yep it's got that wheel in front to lead the way)
 
CS to FP and back again

Post a picture of what you have. If you have the adapter and the steel line in place, your good to go. The S.S. Line is expensive. Its a little added weight in trade for the easy conversion to CS later on. Piercing the inner plate and replacing the outer cover is fought with issues if the cross over oil tube is damaged in any way.
 
Set up for CS

Not able to get a picture easily. My engine is all set up for CS operation. I have the SS line from the front to rear and the governor port is covered with the plate that seems to have the notch in it. Best I can tell, I only need to put the front plug in and I'm all set to go with FP. My concern to validate this method since neither Lycoming nor VANs says anything about going this route. Are there any on here that have done this and have had no long term issues?

Thanks for your comments.
 
CS to FP and back again

Best of both worlds. Check to make sure the rear cover plate is the pressure relief style,install the front plug. You should be good to go FP. When you have an extra $10K you can add a CS prop.:)
 
Post a picture of what you have. If you have the adapter and the steel line in place, your good to go. The S.S. Line is expensive. Its a little added weight in trade for the easy conversion to CS later on. Piercing the inner plate and replacing the outer cover is fought with issues if the cross over oil tube is damaged in any way.

The Lycoming documents allow for a flex hose made to a specific TSO specification.

https://www.lycoming.com/sites/defa...d to Fixed Pitch Propeller and Vice Versa.pdf

I was lucky and found a used SS line here on VAF.
 
My decision

I've exchanged emails with Lycoming and they wouldn't even discuss any alternative conversions beyond their Service Instruction. I also had a great conversation with Mahlon a few days ago ( THANKS!) and he gave me a very detailed and complete understanding of the oil flow and the conversion process. Key here is that if I ever decide to change back to CS, replacing that inner plug is difficult without pulling the crank. Lycoming will likely never endorse any alternative mods since they can't analyze all possibilities.

I am in the process of creating my own Work Instruction to document what I am doing now and what steps I would need to follow to convert back to a CS prop. A note to those who have asked about a part number for the rear cover plate with the milled oil channel, mine was supplied by Lycoming with the original engine.

Ken
RV-9A
Caledonia, MI
 
I am very interested in this. I have a new IO-360-M1B that has a plate on the governor pad with the raised area as shown earlier in the photo, I also have the steel line installed from the factory and front plug installed from the factory. Any way to make sure the governor pad plate is the correct one or are all with the raised section good to go?

Thanks,
 
Verify the correct plate.

There are two ways to verify you have the correct plate. The first would be removing the plate and look for the milled channel on the underside. Make sure that there is a matching hole in the gasket where the oil can flow. An easier method is to disconnect the stainless tube and using a plastic hose connected to the rear port (where the SS tube was connected) and blow into the port. You may have to clear some oil from the passageway but if you get airflow, you should be all set.

It seems that Even though Lycoming does not endorse this change to the SI, they are shipping an updated cover on at least the O-320 and O-360 engines to help accommodate the process.
 
As the guy who stated this thread back then I can report that I followed Mahlon?s advice, did nothing to the plugs or anything else and I have 300 problem free hours on my engine.
 
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