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

Thanks for the link Jim.
I see from their website that they have taken over Hepolite.
The Hepolite Oilmasters were not as fierce as the Cords, but they still controlled oil consumption.
I am delighted that the firm still exists.
I am needing some new rings for my 1955 Standard 10, and standard bore rings do not appear to available, so I will be contacting Cordsduaflex as well as Clupets.

Location: Bonnie Galloway

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