Hi Steve. I remember the first time I "refreshed" an engine (think it was a 1600 Ford Pinto?) which had this type of ring. The gaps were acceptable but the rings slid in and out of the bores so easily I scrapped them because I thought they'd lost their tension! I fitted a set of Cords in their place which gripped well so I was "happy" but became a little less happy a few weeks later when a Ford friend told me the genuine Ford rings are all like that because they are low friction! The engine was fine though and eventually became my demo stand mounted engine which I used in my community ed evening classes.
Although retired I still have a number of garages where I'm a "weel kent face" and drop in regularly for a chat - and cup of tea if I'm lucky and their're not too busy. They know the passion I have for cars so sometimes show me "interesting stuff" lying about the workshop and I've noticed some pistons with the black (Molybdenum?) anti friction pads on their thrust sides, are showing wear such that the aluminium of the skirt is showing through. Of course I don't know how many miles might be on them - many have suffered damage due to getting intimate with their valves - but I wonder how long it takes to wear like this and does it really make that much difference anyway?
Inlet tract carbon fouling on direct injection petrol engines is a great interest of mine. Of course it's been quite a problem on diesels for many years. I'm particularly into VAG "stuff" and I've seen manifolds (and EGRs) so clogged with carbon you wouldn't think the engine could run like that. Some interesting procedures are tried by some:
I've been running Archoil 6900-P Max in the Ibiza since she was new. This product:
https://www.powerenhancer.co.uk/archoil-ar6900-p-max-advanced-petrol-synthesis.html claims to reduce inlet carbon fouling. Who knows, and I doubt if it'll eliminate this "scourge" but It'll be interesting to see how long she goes before I get any symptoms.
