I've done some canning with pint and half pint jars. Haven't killed or
sickened anyone yet. Recently a friend gave me a dozen quart size jars
and I'd like to can some salsa in them. Is the jar size one of those
aspects of canning recipes that can be unsafe to change? Should I look
for a different salsa recipe that specifies quart jars in the end
step? I really don't want to give anyone botulism for Xmas.

I realize the amount of air space or whatever you call it at top of
jar might need to be different for quart jars than for pints. Is there
a rule for that, or does it depend on exactly what kind of food you're
processing?

Thanks for your help!