[Healeys] Ring Choice - closing the loop

[m.g.sharp at sympatico.ca]

Many thanks to everyone who responded to my question about the rings.  Seems
that there are examples of people fitting that fifth ring and leaving it
off, and no-one reported a problem or bad experience either way.  It also
seems there is no hard knowledge on why that bottom ring was fitted, but
several of us, me included, think it may have been aesthetic: simply to
reduce the noise from piston slap.  I thought Earl's response was most
telling in that he had been through a complete engine cycle (i.e. he is on
his second rebuild after 140,000 miles on the first) with a 5-ring piston
and there were no issues noted on the strip-down and good performance.

 

While I have no doubt that extra ring may result in extra friction and rob
the engine of a horsepower or two, no-one has measured it, so we do not know
if that is significant in any way.  The only other potential down-side is
that the bottom ring will scrape the oil from the cylinder wall on the
down-stroke, reducing lubrication on any piston-cylinder wall contact
between the two oil control rings.  However, the bottom ring may also
prevent the piston from making contact with wall, or at least reduce the
friction, so maybe that is not an issue.

 

My goal is a well-built, reliable, original car with factory-level
performance.  Given that, and some concerns about the unknown consequences
of an empty ring groove, I am electing to install the 5th ring.  Also, I
think there is wisdom in Hank's comment that as a general rule parts should
be installed as the manufacturer intended - who are we to second guess the
engineers who thought it necessary to add that ring?

 

Interesting discussion, and if anyone ever turns up hard engineering
evidence as to why that extra ring was added, I would be very happy if they
would share it.

 

As always, this list is amazing for providing a forum for providing a forum
for discussion on the things we find interesting - as arcane they may be!

 

With thanks, Mirek

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20210419/72d7f95f/attachment.htm>