I have a 454. The other day when after I changed the oil, started it up and while it was running I looked under the front end to check for leaks. I saw that the crank pulley seemed to be wobbling like it was out of shape.
1. Is this normal
2. What could cause it
3. To replace the pulley, how much of a job is it to do and how to do it ?
Assuming you checked Richards suggestions first.
2) Maybe someone used it to support the motor while changing a motor mount? or maybe it just got whacked with road debris.
3)Remove the belts, then the 5/8 center bolt (it will be or should be torqued to about 60 lbs.) then the three smaller 3/8 fine bolts.
Before you remove it, how much is it bent? A little wobble won't hurt anything but I have straightened them with a broom handle.
This can be dangerous so be careful. The broom handle can be used much the same way as a tool used to shape aluminum pots and pans and other things made on a lathe. With the engine idleing and all the belts off for safety, you can apply pressure to the pulley and if it's not bent too badly you can control how much pressure you use and it will straighten. In 1987 The Oldsmobile Cutlass equipped with the Chevy 305 had a very noisey power steering belt due to misalignment (Chevy screwed up and made the pulleys wrong) There was a bulletin out describing how to fix this using the same method. It was quickly removed after a couple of guys got hurt doing the repair and new pulleys were made.
I have fixed bent hard to find pulleys by putting them in a jig on a lathe and shaping them. I wouldn't suggest you try the on the car method unless you know what you're doing.
You may want to check the keyway on the crank itself. I had a 383 that had a crank pulley that was always wobbling and had to keep tightening the center bolt. It turned out that the center bolt threads were stripped and the keyway got destroyed. The slots in the crank were elongated and there was no way the keys could ever stay in place.
I'm not sure if the stripped threads damaged the keyway or if loose keys caused the threads to strip. All I know is that I had to get a new crank!!