Base timing vs engine temp?

So this is one I thought I knew the answer to but I've managed to confuse myself. Does base timing change with engine temperature? For example say you said the distributor to 0° when the engine is Stone Cold. Does it Advance or retard as it warms up? All the manuals say the set base timing hot, which would leave me to believe it does change with temperature even though I'm not seeing it right now on my timing gun.

I don't have an answer for you that isn't a guess so I am here to be educated. 

I assume we're talking old school distributor ignition.  In that case the "set it hot" direction is because the engine won't hold a steady idle RPM cold with the vacuum advance unplugged.

It depends, a lot of times an OEM ecu will use timing advance for idle control or idle up features. If this is an old school type distributor it's likely only done only to make the adjustment at one consistent point where the engine is most likely to operate.

Old school carb engine and standard distributor. So, no ecu changes based on coolant temp. Vacuum advance disconnected. 

I can definitely see the "doesn't idle well cold" being the reason. 

But does timing actually change at all as it warms up? 

No.  It's based on engine speed and vacuum only.

Not temp by itself, but the engine rpm vs mechanical advance could. Really depends on how flat/not flat the mech advance is between 500-1500 rpm which can be very distributor specific.

On an analog engine it had better not change with temp. I also know that it is impossible to read until the engine is warm and the choke kicks off because it jumps around too much when reading with the timing light.

On a digital engine I imagine that there could be a timing value for cranking, cold running and warm idle. 

Theoretically, you would also want to make sure the distributor is fully warm so that all of the mechanism works with all of the designed gaps and whatnot.  But I doubt it makes much of a difference.  Most of it would be there to just make sure the fueling is warm and stable.

Thanks everyone. I appreciate it.

The engine will expand and change timing a little.

You also check it hot to guarantee you are at hot idle, and not on the choke, which might have you up into some mechanical advance.  Always set timing with the advance mechanisms all the way down, and always set up your advance mechanisms so they are all the way down at idle.  To do otherwise invites a floating idle speed.

I do, however, want to point out that the opposite is true:  engine temperature can change with base timing.

For years my old Poncho ran a little hot, and I chased my tail trying to diagnose cooling system issues.

Then I did points and plugs and found out base spark was advanced too far. Fixed that and it never ran hot again.