Don't confuse a few degrees out on a newer tech auto to one that depends strickly on Mechanical linking of the valve, distributor, FI pump and linkage geometric timing. There is no computer to change the spark, richen the mix via a sensor[o2], etc.
All of these on 113 are factory set using mechanical calculations and are all dependant
on correct timing which starts with the timing chain. If anything, this is more
critical than on a computer controled system.