How crucial is the vibration damper that sits on the end of the crank? What would happen if it wasnt there? The reason is i dont need the pulley that is on it any more, and its quite large, meaning id have to fit quite a large trigger wheel, removing this and using another pulley would mean i could have a good size trigger wheel, and lose the unnecessary pulley

It is important for long crank life; torsional vibration at the harmonic frequencies of the crank can considerably shorten its fatigue life. Lots of people run engines without them though.

[Edited on 27/2/10 by MikeRJ]

Depends on how long you want the engine to last. They are more important at higher revs but sometimes there are resonant revs lower down.

On v8's they are critical and changing piston and rod specs involves changing dampers. I believe horizontally opposed engines are similar but dunno about straight 4's

Cheers