Chas wrote:
"Christopher Tidy" wrote in message
...


Tom wrote:

Christopher Tidy wrote:


Hi,

As everyone was so helpful with my last question about piston rings, I'd
like to ask another. I unwrapped the new rings for my Wolseley engine
this afternoon ready for fitting. Surprisingly there were four rings in
the pack, whereas there are three on the piston. The first two rings on
the piston are identical plain cast iron rings a little over 1/8" thick.
The third ring is a slotted cast iron oil control ring about 1/4" thick
(the bore is 3"). In the packet I have two identical rings which fit the
first two grooves fine. Then I have a slotted oil control ring which is
narrower that the original (perhaps by 1/16"), and a very thin ring
which is about 1/16" thick. When placed together these two rings are the
same thickness as the original oil control ring, and fit neatly into the
groove.

So it would appear that I am intended to replace the original oil
control ring with two rings. Is this common practice when the correct
ring is unavailable? I bought the rings a few years back and now I have
a vague recollection of some discussion about this, but I can't remember
the details. I just need to decide whether it's okay to fit these rings.
I should point out that this is a big, chugging engine which isn't
highly stressed (1.5 hp at 700 rpm with a 3" bore) so it's probably
going to be more forgiving than modern engines. What do people think?

Any suggestions would be much appreciated.

Many thanks,

Chris


The thin ring is only a spacing ring to convert the wider original
ring to the more modern width. The thin ring is fitted above the oil
control ring in the groove.

Thanks for all the helpful responses. It seems like these rings are
fine. But I'm not sure whether to fit the thin ring above or below the
oil control ring; there seems to be some disagreement here. If it helps
the thin ring is approximately 1/16" thick and rectangular in
cross-section, with a very small rectangle removed from one of the
outside corners.

Chris



That would indicate a scraper ring which should be placed above the slotted
oil ring with the rectangular groove next to the slotted ring, ie facing
down. You should also check to see if the slotted ring is symmetrical or
has a reduced diameter on one side. If so, this side should face upwards to
the scraper ring. Most rings in non-symmetrical ring sets have the upper
face marked in some way.

Thanks very much for the clarification.

Chris