Chevy starter cranks really slow

I just bought an 81 Chevy SWB truck, 106,000 miles. It has several
problems ,but I just replaced the intake manifold (edelbrock) and
carb. (holley) and now my starter seems to turn over very slowly, like
something is binding. I just replaced the battery, no change. Can a
worn out starter turn slowly or can this be related to the work i just
did. (ign. timing etc...) It seemed to turn over normally before I
worked on it.