You don't have to do anything to take the cap off. I was talking about removing the entire destributor. If you look down at the base of the distributor, you will see a ledge that the little clamp down holds. Mark that ledge and the block with a Sharpie so that you can put it back the same way. Take the cap off and then mark the position of the rotor on the outer plastic housing. Remove the bolt that holds the clamp down and then remove the distributor. Don't lose the clamp down. Put a shop towel or something in the hole you leave behind. This should give you all the room you need.
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351W 89 Mustang GT Convertible