Rebore one pot only?

[Matthew Beaubien]

Ameer,

>>Well, didn't think this would be much of a controversy. The price you're 
getting for pistons is insane. I can get custom forged pistons w/ pins for 
about $100 each for 5kT. Check out a custom piston place, they might be 
able to help you, and forged pistons are much stronger and knock resistant 
than OE cast ones.<<

If you wanted just one, it would probably be more than $100.

>>Oversize pistons aren't the same weight, they're bigger. <<

Have you looked on the underside of a piston?  There are pads under there that are used to balance pistons.  The weight of an oversive piston and wristpin are likely the same as the existing assembly, but if not, the piston can be easily "massaged" to bring it in line with the rest.

>>And the 
counterweights are there to balance each other, not the piston and rod. If 
the counterweights are not balanced, you will have vibration, b/c gravity 
pulls one end of the crank down more than the others.<<

Not exactly true.  I'm pretty sure an 4 cylinders and straight 6's are the only configurations where you can change the "bob" weight (i.e. piston/pin/rod weight) without having to rebalance the crankshaft.  Take your everyday V8 and if the bob weight is changed, the crankshaft _must_ be dynamically balanced.  This involves adding/removing weight from the counterweights of the crankshaft to obtain a proper balance because the counterweights are used to counteract the weight of the piston/pin/rod.

Gravity has nothing to do with it.  

>>In fact, you 
can balance an engine by balancing all the parts separately in sets. All 
pistons must be the same, all rods must be the same, all counterweights 
must be the same.<<

Not true.  If the parts are matched as you state, they will be statically balanced.  As soon as the engine starts turning, this may or may not be the case as I mentioned above.

I would not worry about fixing the one hole and putting it back together.  The CR would not change enough to matter, if at all (dish volume may be different).  The balance issue is not an issue if the pison/pin assembly weight the same as the current pieces.  Sleeving isn't always the best option as it is a pretty major operation and a lot of material gets cut away.  Things can move around when you do things like that.

Hope that helps.

Matt Beaubien
'86 5kt
'73 911E