Ford Dura-spark distributor recurving instructions
Step 4
Decide which slot you want to use and if necessary
remove the upper advance shaft retaining clip and
springs so you can lift and rotate the shaft in to the
proper position. If ordering a distributor from a parts
store ask for one for a 1975 elite with a 460 4v engine.
You will be more likely to get the lower number
advance slot like a 10L or 13L rather than the 18 or
21L's. If you have a distributor with the larger
numbered slots limit rotation via welding the slot
smaller or placing a bushing around the pin to limit total
shaft roatation.
click for the big picture
Step 6
install the springs from the
recurve kit and bend the tabs to
keep tension on both springs so
the advance shaft returns to its
idle position
click for the big picture
click for the big picture
Step 7
Reassemble in the reverse order.
Breaker plate, Reluctor, Vac
advance dashpot and return the
little clips to their proper place.
click for the big picture
Place the reluctor back on the shaft in
its original position and align the roll pin
slot in the reluctor with the roll pin slot
on the upper distributor shaft. Carefully
place the roll pin into place after fully
seating reluctor on shaft and gently push
it back into place with a hammer and a
small punch. The 1/2 slots in both the
reluctor and in the shaft together make
a round hole for the roll pin.
Step 8
After complete reassembly of your distributor
again make sure that the upper shaft returns to the
idle position via spring tension. Adjust the spring
tension adjustment arms so that the shaft returns
to the idle position via spring tension if necessary.
You can access the  adjustment arms through the
square access hole,  adjust tension when the
distributor is in the engine and you can check
RPM to full advance with a dialback timing light.
The shaft has to be still to make this adjustment.
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Typically a high performance application needs full centrifugal
advance in by 2,500 to 3,000 rpm. Towing and heavily loaded
combos typically need to have full advance delayed to 3,500 rpm
or thereabouts. Each combo is unique and you will have to make
adjustments based on expected use and Compression Ratio.

                                                               SMJ / RHP    12-02
To figure approximate slot width
for a given advance figure
Multiply the number of desired
centrifugal degrees by .013"
then add .150" to account for
the width of the stop pin.
8L slot =  16 degrees centrifugal advance = .358"
9L slot =  18 degrees centrifugal advance = .384"
10L slot = 20 degrees centrifugal advance = .410"       Total slot width
11L slot = 22 degrees centrifugal advance = .436
12L slot = 24 degrees centrifugal advance = .462"
13L slot = 26 degrees centrifugal advance = .488"
14L slot = 28 degrees centrifugal advance = .514