[Kenth]

1970 Pontiac (GM) did not use vacuum advance at idle speeds due to the TCS system.

1112008 uses a 1115365 vacuum advance unit, starts @8-10 in/hg max 20° @ crank (10° @distributor) @15-17 in/hg.
Last three digits of the part-# and the amount of crank advance is stamped on the bracket on original units.

The 19110657 (stamped B1) vacuum advance is close but only 16° advance, starts@8-11 in/hg max @16-18 in/hg.


I would use the TCS-system or a ported vacuum source for the original vacuum advance and forget it.