0-320 Narrow deck case splitting plate plans and 4 cylinder hold down plates

moto657

MEMBER
Canyon Lake, CA
I’m in the process of an engine OH on my early O-320. Last week I purchased an overhauled B2B narrow deck case. Now I am getting the engine torn down to send out crank etc for inspection/overhaul.

1. Does anyone have dimensions to build a narrow deck case splitting plate? Or does anyone have case splitting tooling they would loan out?

2. Does anyone have a set of 4 good cylinder hold down plates they want to sell? A friend had 4 that I bought this week. I need 4 more to make a complete set.
 
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Used my plates as per the KP article. Worked fine. Just have to leave a bolt in the oil pan area and back it off as you spread to keep it even. Picture rotated .
 

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Used my plates as per the KP article. Worked fine. Just have to leave a bolt in the oil pan area and back it off as you spread to keep it even. Picture rotated .

Thanks for the pictures. So your tool pushes on the crank through a brass block? I think I would prefer to use a tool that pushes on the through studs to separate.

Looks like you pulled the through studs out first. Did you double nut them or use a stud puller tool?

PS - I grew up in Constantia, NY. Really small town not too far from Frankfort.
 
I could make a 3D model in Solidworks based on the dimensions and make a cut file (G-code) from a DXF. I can get my hands on either of the two styles, the old cast with webs or the new solid billet one. I could email the DXF or code in a text file and then you could have it waterjet cut or lasar cut on 1/2" HRPO steel plate.

Todd
 

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I could make a 3D model in Solidworks based on the dimensions and make a cut file (G-code) from a DXF. I can get my hands on either of the two styles, the old cast with webs or the new solid billet one. I could email the DXF or code in a text file and then you could have it waterjet cut or lasar cut on 1/2" HRPO steel plate.

Todd

Is it possible for you to do a simple 2 D layout of the holes to allow the non-through studs to pass through the plate? I think it would be really simple to drill a plate at the home with those measurements. It would be nice to have some accurate dimensions of the hole locations though.


Then use some stand off nuts with washers welded on to pick up the studs and push the case halves apart with the through studs.

Similar to what this guy did:
https://youtu.be/l54p3xtSj2U?si=vCV9Or5whnHcgsz4
 
I could make a 3D model in Solidworks based on the dimensions and make a cut file (G-code) from a DXF. I can get my hands on either of the two styles, the old cast with webs or the new solid billet one. I could email the DXF or code in a text file and then you could have it waterjet cut or lasar cut on 1/2" HRPO steel plate.

Todd
I have those plates as well but need to see which engine they are for. Got them at an auction a few years ago.
 
I have those plates as well but need to see which engine they are for. Got them at an auction a few years ago.


All engines that employ thru bolts dowels. Look at the holes they are elongated. Really needed for pre torque when using high crush bearings.
 

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Good to know. I see what you mean now. Will work on both.
Right is for narrow deck, left is wide laying over the universal Lycoming tool.
PXL_20231113_134342400.MP.jpg
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Thanks for the pictures. So your tool pushes on the crank through a brass block? I think I would prefer to use a tool that pushes on the through studs to separate.

Looks like you pulled the through studs out first. Did you double nut them or use a stud puller tool?

PS - I grew up in Constantia, NY. Really small town not too far from Frankfort.

Narrow deck the through studs are double threaded and screwed into the case on one end. Really doesn't take a lot of pressure to seperate. Just need to do it in the right place and depends on what was used to put it together. Once you get it started no big deal. Nothing wrong with pushing on the crank. Strongest thing in the whole deal.
 
I agree. I have split cases with plastic wedges and have the case splitters makes an easy job of it. Just make sure you have every fastener removed or you can chase your tail. Been there and done that. 8)
 
So separate with slide hammer on cylinder base nut. Install and preload bearings with torque plates. The SI for crankcase preload has been rescinded.
 

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I have used the slide hammer on the wide deck and it is pretty easy and quick. Like Frank posted, the narrow deck has the studs screwed into one crankcase half instead of pass through like the wide decks.

I maintain a couple of Cub Crafters NX Cubs with the IO-390 and like it that Lycoming has made all of those manuals available online. Saves money and the latest version is always available. They have also gone further in depicting things in pictures.
 
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