[tschmidlin]

It depends on how you carbonate.  If the pressure is steady then it shouldn't speed carbonation, but if you turn your gas off (which a lot of people (including me) do because of leaks in their system) then more headspace will cause over carbonation faster if your beer/headspace are not in equilibrium.  If they are in equilibrium should have no effect, and if you keep the pressure on then I don't see how it would have an effect either.

More head space won't cause over carbonation any faster than with a constant pressure applied. In fact, the constant pressure will accelerate it, because by removing the CO2, the pressure will drop during serving and more CO2 will come out of solution.

No, more headspace won't cause it to carbonate faster than with constant pressure applied, that's not what I meant.  I carbonate my beers by putting pressure on the keg and then turning the gas off, repeat as necessary until it is carbonated.  I do it this way because I have leaks in my system that I have still been unable to track down.  The amount of headspace in a keg has a large affect on carbonating this way because more headspace equals more CO2 at the same pressure, so more that can be absorbed by the beer in between the times you add gas.  That is what I was talking about.

[HydraulicSammich]

So, Tom.
A little of subject but talking pressures.  I have recently got my lager temps under control.  I have several kegs lagering.  When I keg and pressurize the head space for extended lagering, there will be no pressure in a few days.  I suspect it is being absorbed?  Is there a problem with little pressure in the head space?  May I continue lagering and not worry about it?

[majorvices]

I carbonate my beers by putting pressure on the keg and then turning the gas off, repeat as necessary until it is carbonated.  I do it this way because I have leaks in my system that I have still been unable to track down. 

Amateur.  Come on man. It's not hard to track down the leaks. Maybe you need to rebuild your regulator. Or stop hand tightening your connections. Or find that one missing white nylon washer.

[tschmidlin]

So, Tom.
A little of subject but talking pressures.  I have recently got my lager temps under control.  I have several kegs lagering.  When I keg and pressurize the head space for extended lagering, there will be no pressure in a few days.  I suspect it is being absorbed?  Is there a problem with little pressure in the head space?  May I continue lagering and not worry about it?

How much pressure are you putting on?  If you are disconnecting the gas, I would put 20+ psi on each keg to make sure it seals and to hopefully leave a little pressure in the keg as the gas goes into the liquid.  The only problem with not having pressure in the headspace is that the keg may not be sealed, which could let air in.  You might hit it again after a few days, or just force carbonate as you lager.  There's nothing wrong with lagering under pressure.

[tschmidlin]

I carbonate my beers by putting pressure on the keg and then turning the gas off, repeat as necessary until it is carbonated.  I do it this way because I have leaks in my system that I have still been unable to track down.

Amateur.  Come on man. It's not hard to track down the leaks. Maybe you need to rebuild your regulator. Or stop hand tightening your connections. Or find that one missing white nylon washer.

It's a 5-way secondary regulator bank - last time I spent time trying to find the leaks I found 8 of them and got them tightened down.  It's a lot better, but not completely tight yet.  I suppose it would have been more accurate to say I "haven't spent the time" rather than "unable", but it's on my list of things to do

[majorvices]

When you walk in and find your 100 lb tank of Co2 is empty the day after you put it on you get pretty good at finding leaks. 

[bo]

So, Tom.
A little of subject but talking pressures.  I have recently got my lager temps under control.  I have several kegs lagering.  When I keg and pressurize the head space for extended lagering, there will be no pressure in a few days.  I suspect it is being absorbed?  Is there a problem with little pressure in the head space?  May I continue lagering and not worry about it?

When I get a keg ready for lagering, I always rock and roll for a few minutes to get some CO2 in solution. That little head space won't come close to making up the pressure lost because of the temperature drop. I actually had a keg create a vacuum doing that.

[tschmidlin]

Good point, I assumed the beer was already crash cooled before racking.  if it started warm, between the beer shrinking and the CO2 absorption you'd need to dose it with gas a few times to make up for the pressure drop.