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(Frank) wrote in message . com...
Cool! I'm rebuilding the 454 in my Sea Ray and man what a job. My
question is, what is the most I can take of the cylinders and still
use stock pistons? Some water go into 3 cylinders last year and left
some pitting. After a lot of honing most of it is gone, but I thing
some machining will be necessary. I can post some pics if it helps.
Thanks.

Frank: you can have the cylinders bored out by a good engine rebuild
shop. They'll determine how much - 20, 30, 40, 50, 60 thousandths of
an inch - based on the depth of the rust pits. They'll also advise you
on the limits required to keep using the stock pistons.

Ideally, you don't want to increase bore diameter more than necessary.
I've gone 20 thou over with stock pistons. Any more and you risk
increased piston slap; it happens when the pistons rock from side to
side during travel. When this occurs, the piston skirts experience
more shock and can start fracturing over time.

However, if the honing has pretty much removed the pits and there's
little more than a surface stain left... and you can't really feel a
change in surface smoothness when you drag a fingernail over it... you
can assemble the engine with a new set of rings on the stock pistons
and it will run just fine. Be sure, though, to put an old ring in each
bore and measure the end gap with feeler guages at the top, middle and
bottom of the cylinder. This will give you an idea of what the run-out
is. If it's only a few of thousandths of an inch, you'll be fine. If
it's like 10 thou or more, you should bore to get them all uniform.

You can buy new ring sets that have enough 'meat' on them for
hand-fitting. You slip the rings into the bores, find the smallest
diameter in the travel path, file the end gaps until you get them just
right. There are specs to keep in mind (usually come in the box) - you
want enough gap so they have room to expand when heated up yet not too
much to pass oil and allow blow-by (compression leakage). You also
want to stagger your ring gaps so that they are at opposites to each
other - i.e. the second ring gap is 180 degrees opposite to the top
ring gap, and on down. If you line them all up (as some guys have
done), you get max blow-by and oil consumption.

For those of you who wonder... I am new to this group, a retired
mechanic with 35 years' experience, and own a great 24' Doral Tara
running a 4.3L Chev V-6 thru an Alpha One Merc outdrive.