Yep, I've got a 4100 on a factory '66 four barrel intake and the linkage won't clear without a spacer. Make sure you compare the surface area on the top of the intake manifold to any spacer you might get, it can be a headache finding one that doesn't allow for leaks. Especially if you want the vacuum line on the rear.It might need a spacer to make room for the linkage to clear, maybe someone with a 4100 on an original intake could take a look.
A leak in my spacer caused coolant to enter my motor and grenade my engine...grrrrr.... I am having my spacer's coolant passages blocked for now until I can find a replacement. I would like to have the spacer to keep it original.