DISTRIBUTOR TUNING

Duraspark Ignition Advance Curve Modification

One problem I have found with modifying my Stang was the stock advance curve did not work right with a modified motor. It is necessary to re-curve the vacuum advance of the distributor. Crane makes a kit for doing this. I would suggest getting it. If not you will need a adjustable vacuum advance mechanism for the dist. and an assortment of distributor advance springs. The following are instructions for doing this modification. This info was written by Johnathan Knapek.

 

Re-curving the Stock Advance Curve
Written by John Knapek
  1. Remove the dist. Cap.
  2. Loosen the 2 retainer clips and remove the plastic dist. Body.
  3. Remove the C-clip holding the vacuum advance arm in place and lift the arm off the pickup coil assembly.
  4. Remove the 2 screws holding the vacuum canister in place and remove the canister.
  5. Using a couple of flat head screwdrivers, pry the armature (the 8-cog gear looking device) up and off the main shaft. Be sure to keep the dowel pin that holds the cog in place.
  6. Remove the two screws holding the base plate down. Then remove the base plate.
  7. Remove the mechanical advance springs keeping track of their original location and installation.
  8. Remove the circular felt pad from top of the main shaft.
  9. Remove the circular clip, which sits under the felt pad.
  10. Lift the governor (Main shaft) and turn it 180 degrees so that the narrower end surrounds the positive stop position at the base of the dist. You’ will know the positive stop if you move the governor back and forth. It’s the small metal extension.
  11. Once the governor has been turned 180 degrees re-install the weak advance spring and install the yellow spring provided from crane kit to replace the heavy Ford spring. This will put you close to 2800-3000 rpm for total advance.
  12. Slap everything back together installing the Crane Vacuum unit in place of the original Ford unit.
  13. Move all your spark plug wires 180 degrees around the dist cap. Each wire should end up directly across from where it should normally be.
  14. Start your engine and reset your initial timing to 10 to 12 degrees.
  15. If you have a pinging at mid-range, use the instructions in the Crane kit to tighten up the advance canister. If there is no pinging at mid-range, loosen up the canister until you get pinging, then tighten it up 2 turns.