Has anyone out there had any experience of using Clupet piston rings on Austin Sevens? Basically the ring is shaped like a keyring and goes round nearly 720 degrees (2 turns) I know they have been used with steam engines and some racing motorbikes, also they are made in Cumbria. The concept seems good but.............?

Bob

Location: St Tudy North Cornwall

Sounds a little like the infamous Cords piston rings. If I remember the results of using these was described by one of the Austin 7 greats as - 'the wear was fumonial and likened unto a barrel'

Never found out what fumonial meant.

I believe still available.

Cheers, Tony.

Location: Malvern, Victoria, Australia

probably meant "phenomenal"

Location: Gard, France 30960. Used to be Languedoc-Roussillon but now it's Occitanie

or 'funereal'...

Location: Cambridge

Probably more crematorial, Hugh. I think the word might imply "smokey".

Regards,
Stuart

Interesting to note that Clupet rings go back at least as far as the 1920's.

Picture of the type of rings described at:
http://www.practicalmachinist.com/vb/antique-machinery-and-history/clupet-piston-rings-150209/

Steve V.

Location: Polegate, East Sussex, United Kingdom

Thanks Stephen for posting that image of these rings.

As you can see they bear no resemblance to those much maligned 'Cord' rings.

In the case of Clupet rings (which incidentally were developed in about 1907,I believe), they appear to rely on low contact pressure around the bores, compared with the thin elements of the 'Cords' which maximise contact pressure around the cylinder. I would imagine that only the top ring would need to be of this type to provide good compression with conventional scraper rings fitted lowe down.

I tried to add an image at the start, but guess what - Photobucket wouldn't let me!!!!!, and I'm not prepared to waste any more time on it. It even rejects the AVATAR that it always allowed me to provide. Call this progress!

End of rant

Kepp the comments/opinions coming - I may be tempted to get a set of 4 made!

Bob

Location: St Tudy North Cornwall

Ps I was making the effort to upload a photo but photobucket is *rsing about
but try this:



Steve V.

Location: Polegate, East Sussex, United Kingdom

Know where you're coming from re Photo bucket, I practically gave up too!

The Clupet rings are an interesting design, the company still seems to be trading -must be worth a go.
As you say, nothing like Cord rings.

Clupet Piston Ring & Gauge Company
Factory B,
Solway Industrial Estate,
Maryport,
Cumbria CA15 8NF

Tel 01900 818 361

Location: Polegate, East Sussex, United Kingdom

Agree- totally unlike Cords Rings.

Question- how do you fit them - wind them on ?

Cheers, Tony.

Location: Malvern, Victoria, Australia

In the steam world they are often known as bore wreckers.

So a slight connection to Cords Rings?

Location: Malvern, Victoria, Australia

In defence of Cords, I've used them moderately successfully several times over the last 40 years or so.
When an engine is burning a large quantity of oil, they were a way of fixing that rather than an expensive rebore. I've used them on, among others, an Austin A40 Farina, a Reliant Scimitar (Essex 3 litre), and more recently a Peugeot engined 2.5 Granada diesel.
The rings certainly fixed the oil burning, but I did not hang on to the cars long enough to be able to assess any bad effects.
In short a cheap substitute for a rebore.
If your A7 is standing at +80 thou with severe smoking and lack of compression, they (or Clupets) might be the answer, seeing as many of our cars don't do many miles.
Standing by for incoming!

Location: Bonnie Galloway

I used a set of Cords rings on my Chummy thirty years ago. The block was cracked and +60 so didn't warrant a rebore but it was gas flowed and had big valves. The oil control problem meant that the 14mm plugs in the HC head oiled up all the time.
The Cords rings stopped the oil problem instantly and continued to work for probably another 10 - 15,000 miles. After that, the block was truly finished and laid to rest.
Shame they are unobtanium now.

Location: North Wiltshire

I used Cords rings when rebuilding a Daimler Straight 8 engine many years ago. They were friendly and helpful and produced rings that fitted the unusual dimensions of the engine.
They still exist in Merthyr Tydfil see
http://www.cordsduaflex.com

Location: Bonnie Galloway

However exotic the ring shape there is free passage behind and blow by is determined by the rectangle formed by the gap times land clearance, hence all the fancy shapes of the past have devolved to the simple butt.

Cord rings were not used on top groove. As compression rings operation obscure as do not operate primarily on normal principle of the gas behind loading the ring. Despite reputation as the kiss of death marketed seriously for decades, even after the 4 piece steel oil ring. became common (now 3 piece)

When i took over my car it was very worn but used moderate oil. We suspected the block was cracked so did not want to rebore. The 5/32 top rings were very loose and on very authoratative professional advice from the Cords agent fitted a Cord ring below as a spacer. The car then used prodiguous oil and all the top rings soon broke, whereupon it burned more.

From 'The 750 Special Builders Guide' published approximately 1954

An article- Building a 750 Formula Car by J French, Page 21, last paragraph-

"I do not use and I will pass no opinion on the special piston rings such as the Cord (sic), but I have seen some blocks on which the wear subsequent to fitting them has been fumonial and like unto a barrel."

I knew I had seen it !

Cheers, Tony.

Location: Malvern, Victoria, Australia