A story about piston rings

[Billmack]

I am recounting my experience here to help others not repeat my travails. A while back I was hired to repair a twin cam engine with low time on a rebuild which had spun a bearing. Engine came to me apart with a wrecked crank and one wrecked rod. 701 block bored .020. Sooo... I replaced the crank with a freshly ground and balanced one replaced one rod recutting the big ends and balancing all four ( new arp bolts) and replaced the rings with a set of deves rings, a brand which I had had excellent results with in past. Put it all together went thru priming for oil pressure and whipped it back in the car and started it up. Sounded great set timing carbs etc. Noticed some blue smoke. Figured rings needed to seat no biggie. Smoke got much worse. Few trips out on highway it runs like its a mosquito fogger. Awful. Was driven on a 50 mile trip back to my shop used 2 qts oil. Pulled head and pan nothing looked horrible except there was oil in the valve pockets of the pistons. Like the thing had no oil rings. PS compression was fine. So a lot of looking at pieces with magnifying glass etc went on. Pistons were used but in fine shape clearance was good. They were made in Italy by a company named Asso, who I was familiar with thru karting. I traced the company down who had originally ordered many sets and distributed them. Was QED in UK. Called asked and received info they thought deves would be fine. Bought a different brand of rings from them, compared to the deves.. Compression rings were wider I.E. made for a deeper groove and more tension. Oil rings were one piece instead of three and had a spring tensioner similar to hepolite. Put them in put back together and car was driven yesterday all's well. What I saw as the problem is that the asso pistons have a deeper oil ring groove than most and the expander from the four piece rings went too far into the groove to provide any tension. So there you are. Cost me a free tear down and reassembly to find out but all's well that ends well. Engine does really run sweet. Got a cam grind with lots of lift not too much duration. Idles great and did 150 plus on dyno before first blowup (low oil on a track day...).

[promotor]

Cheers for that info, worth bearing in mind.
I have used Deves rings in the past but didn't fit the oil rings as I just didn't like how they looked. It was a while ago so perhaps the ring depth was something else I noticed as a reason not to fit them.

[Billmack]

I've built tons of mg and triumph engines with them never had trouble till then