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MG MGB Technical - Oil Control Rings

On the subject of engine rebuilds & rings, it seemed to be the case (back in the eighties/nineties) that instead of a "rebore- new pistons - new rings" rebuild that after honing (if needed) an option was to use oil control rings to cut down the rebuild cost.
I believe the concept is that they were tighter sprung against the walls than standard rings - trying to take into account the increased diameter of the cylinder bore created by wear. I used them on a a midget rebuild in '89 and it seemed successful. Not sure of the downsides.
However, not much is heard of oil control rings now and I wonder why - anyone have ideas? Have they been superseded by a new device? A google comes up with few references - apart from 2 companies - Hastings & Grover who do them, but not much from folks discussing them.

I know there are engine gurus out there and I would be interested in your comments (as I have such a potential engine)

Regards, Graham
Graham Moore

Graham,
You might be interested to read the Trilogy of the Rings on the Total Seal website http://www.totalseal.com/
I am believer in their file-to-fit rings as a way of getting the best fit for conventional engines. Also worth a read is their technical page.
http://www.totalseal.com/TechPage.aspx#trGaplessPistRings
Mike
Mike Ellsmore


In Australia the ring of choice for a worn engine was the "Cord" ring. Each ring was made up of a multiple of dished shim rings. One dished up then one down until the ring groove was full. They were great, lasted and performed well. They got a name for pulling the top off pistons but this was only because they were often fitted to an engine that was about to blow up anyway. If they were fitted to an otherwise sound engine they lasted well. Never here of them now but used heaps of them in the old days. I must Google them. Its not usual to fit oversize rings in a re-ring as the bore wears very little towards the bottom of the stroke The gap would close up jamming the piston. There were probably other types of ring designed for worn engines but the Cord was memorable.
I would use them again. Denis
Denis4

I picked up a set of Cords on ebay fairly recently.
Dave O'Neill2

The first time I came across Cords was in a monologue by Blaster Bates, the demolition expert. He recounted how this burly copper wanted to check the brakes on his knackered old van by pushing it with the brakes on, so BB put it in first and let the compression from the Cords defeat him.
Paul Hunt

The compression, or upper rings, are under a lot more tension than the oil scraper rings. They maintain the pressure above the piston needed for combustion. When they become worn, they allow gasses to pass by them into the crankcase where they contaminate the oil and form acids that can eat away at your bearings. Whenever a piston is removed from its bore, all of the rings should be replaced with new ones and the cylinders honed to allow the new rings to seat properly. If not, the rings may fail to seat and you'll wind up with an engine that runs worse than before it was disassembled. RAY
rjm RAY

This thread was discussed between 10/05/2014 and 13/05/2014

MG MGB Technical index

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