Ned: I have done this several times on my 603 engine, I believe it is similar if not identical.
The vacuum pump drive flange on the IP timing device should be lumpy, but it should not be scored or rough in any way. I would say for an average DYI it is not that difficult. There is one special tool I would recommend, and that it the IP locking pin, available from the dealer. Not expensive. What was the symptom from the vacuum pump? I also have a write up when I did mine, let me know if you want it. -- SANTÉ Doug Quance Consciousness: That annoying time between naps. 90% of being smart is knowing what you're dumb at.
