can anyone tell me if the vacuum advance springs in the distributor are all the same or different for like a 318, 340 or 440 engine?
Just to clarify, are you talking about the spring in the vacuum can mounted to the distributor, or the two 'mechanical advance' springs in the distributor?
the 2 in the distributor connected to the weights.
not exactly clear what you are asking , the factory mechanical springs are different , if they have been changed they could be the sme or different by changing only one spring or both with 2 of the same spring or 2 different springs depending what result was desired
The springs were factory tailored to different engines. So the ones in a 318 with 8-1 compression and a mild cam were different than what the factory installed into a 10-1 compression 440 with a longer duration camshaft.
The factory service manuals generally had the specifications for the amount of distributor advance although not the RPM that it was all in at.