Some more info would be useful - such as system, mobo...
Anyway, if you're using a Tbird you may change the CPU default clock multiplier if the CPU is 'unlocked' (L1 bridges intact). Otherwise you can't (you can actually change it in the mobo BIOS, but the CPU will ignore it).
Your memory probably can't handle 140Mhz (or your CPU can't handle the new frequency with its default multiplier).
How terrible is wisdom when it brings no profit to the wise
If you unlock the L1 bridges by penciling them in, then you can change your multiplier by doing the same thing to the L6 bridges, but choices are limited by the default setting. The L7 bridges can be used to change the voltage even if your motherboard can't. The settings are listed in one of Tom's early articles on overclocking the socket a cpu. You must be patient when trying this, and use a heatsink that is easy to remove and install, because I wouldn't start up your system without the heatsink installed for even a few seconds.
Raise the core voltage to 1.85v. Raise the I/O voltage to 3.5v. Make sure you have good memory. Lower the Cas latency if necessary. Most AMD "C" chips can hit 150MHz at least. Some "B" chips can also. Knowing your manufacturing revision helps, an Axia or AYHJA can go higher than others.