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Timleech

National/RN liner differences

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I've been aware for many years that there were differences between the cylinder liners for the two brands of engine, but until now never had to deal with the issue and didn't know exactly what the differences were.

 

I'm posting this in case it's helpful to someone else contemplating fitting new liners into their National.

 

Here's a National liner alongside a new RN liner:-

 

ebOiGDg.jpg

 

Actually the difference visible in the pic isn't what matters. Old RNs had the same sealing system at the bottom, a gland screwed up from below which compressed a rubber ring The new liners use the more conventional O rings sitting in grooves in the liners.

Thde significant difference is that the National liner is 1/8" bigger in diameter at the top, both the shoulder and the machined area just below.

The RN liner has diameters here of 5.125" and 4.875", while the National uses 5.25" and 5".

Both have the same 4.875" diameter for the lower landing.

The National arrangement is far better, as anyone who has had to pull corroded liners out of an old RN can tell you. Having the same diameter top & bottom can mean that force is needed all the way up, until the liner is pretty much clear of the top of the block.

Worse, with the conversion to O-ring seals, these have to be forced through the same diameter at the top, when fitting new liners, as the diameter they seal in at the bottom, and with no 'lead' to help them in, so there's a serious risk of the rings getting damaged before they even reach the bottom. That's not a problem with the National dimensions - the trouble is that National liners are to the best of my knowledge an extinct breed (someone will probably post now that they know where there's a shed full!).

The issue is how to make the RN liner fit properly into a National?

As with most engineering jobs, there will be more than one way to skin the cat, but this is what I did.

Why not use the tops of the old, worn, National liners as they already have the correct dimensions?

 

Mytp9IH.jpg

 

Z2xxrDO.jpg

 

FgsBLce.jpg

 

 

0.2" was removed from the lower face of the top shoulder of the new liners, this meant that the sleeve could have some useful strength with that 0.2" included.

 

These sleeves were fitted into place with Loctite 638 high strength retainer, though probably simply assembling into place with a good dose of Wellseal would have been fine.

 

Finished product:-

 

jutuOIh.jpg

 

 

After cleaning out the sludge from the block, some lead was put onto the top of the lower landing to ease the entry of the O-rings:-

 

sH4vgCd.jpg

 

This pic shows the splash plates mentioned in my earier post, they sit on the ends of studs which also serve to compress the liner sealing gland (just about visible):-

 

zUP0RI4.jpg

 

Tim

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Hi Tim, yes the National I have still retains it's splash plates and also wondered if they did anything or indeed were worth saving but decided to stick with them.

I still have a brand new National liner as a spare for when I need it, unfortunately the chap I got it from had thought it a rather suitable door stop to use in his workshop for many years...bless him.

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Hi Tim, yes the National I have still retains it's splash plates and also wondered if they did anything or indeed were worth saving but decided to stick with them.

I still have a brand new National liner as a spare for when I need it, unfortunately the chap I got it from had thought it a rather suitable door stop to use in his workshop for many years...bless him.

 

Had the engine seen service in the GU/BW fleet?

 

Tim

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After cleaning out the sludge from the block, some lead was put onto the top of the lower landing to ease the entry of the O-rings:-

 

Tim

 

Say it quick enough and everything is easy!

 

Nice work Tim

 

Richard

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Had the engine seen service in the GU/BW fleet?

 

Tim

Yes, according to the engine list I have it was originally fitted to the 'Bexhill'.

When it was removed from said boat or it's history thereafter I don't know.

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Yes, according to the engine list I have it was originally fitted to the 'Bexhill'.

When it was removed from said boat or it's history thereafter I don't know.

 

 

OK, thanks

 

 

Tim

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Another thread has led me to thinking more about the splash plates thing.

Nationals were designed to have chromed liners (and incidentally cast iron pistons), plus splash plates.

I've worked on several older RN's, and never seen chromed liners nor splash plates.

Is there a connection there?

As this National will now have (plain) RN liners and RN pistons, would it be the right thing to do to remove the splash plates?

I've seen several Nationals with no splash plates.

I'm undecided, one reason for doing the work was to cut down the amount of oil smoke so reluctant to be doing anything which works the other way.

On the other hand, maybe the plain liners need the full amount of oil splash for proper lubrication.

 

Anyone seen chromed liners or splash plates in an RN?

 

Tim

Edited by Timleech

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I have - not a shed full - but 3 liners for this era - must check the id on the box and maybe someone will tell me they are rubbish or gold - either way. Can't post picture as don't know how to.

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Are the little ends splash lubricated. How effective are the anti splash plates keeping oil off the bore and will oil starvation be a problem with prolonged slow running, could also ask about number and type of oil control rings fitted to each make.

 

Probably need to apologise for these basic questions and need to thank Tim Leech for sharing this information and photographs.

Edited by steamcompound

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Probably need to apologise for these basic questions and need to thank Tim Leech for sharing this information and photographs.

 

Something he would have appreciated. Tim passed away last year

 

He's very much missed

 

Richard

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post-25879-0-73100100-1455542757_thumb.jpg

The liners I have - the boxes are marked "National" - I assumed they were RN - just shows you can never take things for granted. I have tried to add photo with sizes but its not like the pair of liners in other posts would appreciate comments on what they are.

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I know its an old thread, however people use them to research.

Little ends are fed oil up the hollow conrods.

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The following is from the Russell Newbery Register magazine (Autumn 2017) If anybody needs liners it might be worth following up with David Bixter at Russell Newbery

National cylinder liners. We can get a batch of cylinder liners manufactured to suit the national ‘D’ series, which although similar to RN liners are different enough to be a problem. There needs to be a demand for at least 10 liners or the piece price is too high. If we can get orders for 10 or more they are available at £250 each. If we order 48 or more the price will drop to £210 each. Any one interested will need to pay a £50 deposit per liner with the balance due on delivery. Delivery is 8-10 weeks from order placement. These liners are top quality, made in England items.

RNDE Company

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