[Shotimes] Q on installing pistons

[George Fourchy]

On Fri, 1 Oct 2004 09:48:34 -0700 (PDT), Ian Fisher wrote:

>I installed a piston and rod today. How easily should
>the piston "fall" into the bore as it leaves the ring
>compressor? And if it makes some noises, that's ok,
>right? 

It's been a while, but I've installed a few pistons.

The rings will be unworn virginal metal, very finely machined, against the virginal
cylinder wall, also honed to an even rough surface.  This will make pistons very
hard to move after they are installed.  You will need to tap the piston in with the
wooden handle of a hammer.  That is standard procedure in a home garage.  Use lots
of oil.  Each piston you install will make the whole assembly that much harder to
turn over, to position the next journal for its rod end.  By the time you get to the
last one, you will need a pry bar to turn the crank.  THIS IS NORMAL.

Be sure to protect the journals from the rod bolts as you send them down the
cylinder bores.  Cover them with rubber tubing so that they won't nick the journal. 
Been there... done that.  

I've told the list this before, but you can double check the clearances of the
bearings after you torque the rod bolts by tapping the rod cap with a hammer handle.
 If the whole thing rings like a bell, the clearances are correct (as long as you
can slide the rod end back and forth (sideways) on its journal....there should be a
tiny space between the two rods so they can slide a bit).  If it clunks, the
clearance is too loose.  This worked for me as a backup check all through the 70s
and 80s, when I was doing the Boss engine over and over (because it kept burning oil
because it wasn't breaking in, NOT because I was  doing anything wrong!!).  That
also worked for a couple of 289 engines I did during that time, too.

Remember....after 3 or 4 pistons are installed, you WILL NOT be able to turn the
engine over by hand.

As for the piston coming out of the ring compressor into the cylinder.....first,
make sure you have the ring gaps opposite from each other, or at least 120 degrees
apart.  The oil ring, if it is a multiple piece ring, is the same way....the top
edge's gap should be 120-180 degrees apart from the bottom one.  

Compress the rings as much as you can in the compressor, using lots of oil.  You can
tap the sides of the compressor with an end wrench, not hard, but all the way
around, as you tighten it to make sure the rings are fully retracted into their
gaps.  Have the skirt out a bit at the bottom so you can start the piston in the
bore without pranging a skirt.  Use the hammer handle to tap the piston down...it
will be harder and harder to move downward as each ring engages the bore, and there
will be one tougher tap required to start each ring at the top of the bore.  When
they are all started, remove the compressor, and push or tap the piston down to its
bottom travel.  Work on the bottom of the rod and torque it as required.

I know you have gotten half way already, but it's easier to pop them back out now if
you need to to set the ring gaps if you haven't done that.

More later if I think of anything else.

Best of luck!!  It'll be something you can be proud of when it start right up!

George