Either use a hydraulic press, an arbor press, or if you're using an all-aluminum cam gear, heat it to about 400 degrees and it will tap on easily with a hardwood block and a hammer. Don't forget to install the thrust plate and the spacer washer before you put the gear on! Also be sure the timing mark is facing the front.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!