"K Smith" wrote in message
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Better concede that Clam's engines are pretty good in this department
(before "he" has a complete detonation leading to a seizure;-)), they
have lots of tiny diam pistons, so piston/ring temp has a better chance
& just as he says they do have very good service lives, don't know if
the early OB designers were that much cleverer than current or just luck
but whatever, they're a good blind blind proof of the reasoning.

Smart girl (this time)

I primarily deal with the 99ci six (16.5 ci per cylinder) and those motors
do get "coking issues" around the rings if you don't use a decent quality
*ashless* oil. And despite the downsides - I do recommend using a can of
Mercury "Power Tune" as directed, once a year, to try to keep those rings as
clean as possible. I know it washes all the oil out too - but it's only for
a moment. They have a long service life - but you do have to follow all "the
rules".

The one I called a true "lifetime motor" was the 44ci inline four. At only
11ci per cylinder, it's indeed a nice small piston. The real secret of those
though is that the burn efficiancy is lower becasue they never *got* the
"new design" piston. So even though they make only 1hp per cubic inch - they
are running a lot cooler than the 99ci making almost 1.5hp per cubic inch.
You'll see those little 45 or 50hp Mercs running around everywhere - to this
day. They are a post WW-2 design that survived almost intact till the very
late 90's when EPA regs kinda made them look bad - LOL. I picked up a 1958
unit (because it looks cool) and plan to use that for a barge pusher.


-W