61-63/ 64 distributor difference

[demon452]

So I set up a dual quad and i wasnt getting enough intial timing on my 64. Anyhow I have a 63 distributor so I decided to swap some things. Thought at 1st the only difference was the weights until I looked. Seems like the ccw is different as well. Ok everything besides the housing. 

 

Anyhow I am wondering why the ccw is that much different?  The 1st pic is of the slot. The 64 is top and 63 bottom. Is the slot larger on the 64 due to the 63 having more initial timing built in? Not as much movement obviously once the limit bushing is in on the 63.

 

Thanks in advance

Edited December 29, 2018 by demon452 (see edit history)

[Jim Cannon]

The '64 engine is setup differently from the '61-'63 because the earlier engines had Dynaflow and the '64 was the first year of the 3-speed automatic transmission.  Look at the timing curves in the shop manuals for the '64 and the '63.

 

The '64 dual quad engine is a lot like the '63.  Look at the cam specs.