engine rebuild
No big "bang", no sudden loss of
power (surprisingly), just s
ome
smoke and oil
.  Compression
check showed low on two
cylinders.  Upon disassembly you
can see why.  I'm surprised the
rings sealed as good as they did
considering they had no support.   
  
Comptech adjustable cam gears
and reworked oil pump.
The rebuild starts with parts.  With the NSX,
everything is expensive.  Here's some CP low
compression pistons and rings (3.0).  
Oliver steel connecting rods and Cometic
head gaskets
ARP studs and aftermarket valve
springs and titanium retainers
Picked up two complete sets of
heads including the entire valvetrain
(valves, springs, rockers, lost
motion pistons, cams, seals,
everything!  I'll use my original
heads for development work and
replicate the portwork on one of
these sets.  
Honda tries to hold tolerances very tight.  Since the
manufacturing process has limitations, Honda chooses
to take up the tolerances using the bearings.  Based on
crank and block sizes, Honda selects the bearing that
provides proper cklearences and bearing crush.  The
color codes tell you the relative thickness of the
bearings.  Brown is about .0001 to .00015 thicker than
the green.  Were talking 1/10 of 1 thousandth of an inch.  
Here's my engines stackups.  During rebuild, I'll
use Honda's selection of bearing sizes to
create a crank to bearing clearance of about
.0022.  Inspecting and measuring the used
bearings can tell you things about the operating
condition of the motor.  
Checking the runout of the main
bearing journals.  Should be about
.0002 or less.   Dial indicator can
read .0001.  
Inspecting the combustion chamber
and piston tops can also give some
clues to what's happening.  The
darker area indicate that
combustion is taking place.  The
cleaner areas are where little if any
combustion is occurring. The lighter
grey areas is where combustion is
occurring faster and the darker gray
slower.  Piston tops can be read
the same way.  One conclusion that
can be derived is the turbulence
characteristics inside the
combustion chamber
Most modern wedge shaped 4 valve cylinder
heads try to force the charge into as small a
"pocket" as possible.  This promotes a fast
and controlled burn.  Most try and force the
mixture to the exhaust valve side as the heat
of the valves promote a more combustible
charge.  This is accomplished by designing in
a larger and tighter squish zone on the intake
side as you can see.  The squish zone also
create needed turbulence which again
promotes fast, controlled and complete
combustion.
The Block with main caps need to
be measured to determine if
anything's been beat out of round.  
This would require a line hone to
correct.  All the bolts need to be
torqued to spec and the block
soaked at room temp for at least 24
hours before any measurements
can be made.