There can never be too much "amperage" (common term being "CURRENT") offered by a transformer (wallwart, power supply) as a device only draws what it needs from a power supply. There can only be "not enough current," as in the transformer not having enough current to supply the demand from the pedal. Most analog pedals require only 50ma (milliamps) or less! Most adapters offer 200-500 ma or even 1000 ma (1 amp) so you're always going to be fine for that part of the equation.

What you really have to look out for is correct VOLTAGE. USA adapters all start out being fed 120 volts AC from the wall. You need to find out what the OUTPUT of the adapter is, i.e. "12V AC" (12 volts Alternating Current) or "9V DC" (9 volts Direct Current) etc. Most pedals run off a battery... right? A battery is 9 volts DC! So, you'd better make sure that the OUTPUT of the wallwart adapter reads "9V DC" and that the POLARITY is correct.

About POLARITY... does the adapter have the positive (+) going to the correct part of the plug (cable) that connects to the effect? 99% of all pedals have the NEGATIVE (-) (also called ground) going to the Center-Pin of the cable and effect's adapter port. Getting this wrong is what results in 85% of all returned/burnt-up pedals for Fulltone, and for most other manufacturers, I suspect.

Using the wrong adapter and causing damage to your effect voids the warranty and will cost between $30 and $65 plus shipping to repair.