I dug out my trusty vacuum pump and I've been playing with the vacuum advance on my 83 Spirit with the 258. I have a rebuilt distributor that I bought from Jock some time back, so I tried it on there first. I don't see any advance until the vacuum is at about 5 in. It seems to be completely advanced at 15 in. The one in the Spirit is quite different. It starts to advance at 2 or 3 in., and is completely advanced at about 7 in. Anybody know what normal should be? I'm thinking the one in the car probably has a weak spring. I'm also starting to suspect that the mechanical advance has a broken or weak spring too. I'm going to try swapping them this weekend and see if the rebuilt distributor runs any better. Todd