Zack: Are you sure the clocks were running FAST?
A generator must run faster than 3600 rpm to cause clocks (which uses the generator frequency as a time base) to run fast.
Since you measured 115VAC I suspect that the meter you're using to measure the voltage is wrong or you meant the clocks were running SLOW.
You might want to invest in a meter called Kill
A Watt Model P4400.01. They are made by Intertek. This little meter (which simply plugs into a 120VAC outlet or extension cord) gives a digital readout of volts, amps, watts, VA, frequency, power factor and KWH. The accuracy is good enough for our use. The meter can be had for less than $30.00.
I ran an old, 7 turbo-generator power plant for 22 years that didn't have sophisticated frequency control. We used two clocks. One was on commercial power and one was on our system. We ran the generators so that both clocks matched in time. Sometimes we had to run slower or faster to get our clock back to the time showing on the commercial powered clock. With the varying load of our paper mill, this was a delicate balancing act requiring almost constant attention.