Hey everyone. I've been doing research for months and managed to accumulate all of the information and parts that I wanted for my large cap HEI timing distributor. Now I realize this topic has been covered before on several threads on several different forums but nowhere I could find contained all of the information in one place. Dr. Grip, Danny and a few others have provided the details but it's spread out, and for the novice EFI/Distributor guy it's not easy to follow. Thanks to those guys for sure for saying what they have or else I may not have figured it out myself.

Either way, I've assembled a video to show the process I used to make my eBay HEI distributor work in my '67 Camaro. Keep in mind I don't have any financial interest in this post, I just want to get all the information in one spot. I also think it's important for the regular user to realize that this option may not work for everyone and going with a supported distributor like a well built MSD or Holley Dual Sync may be the best option. Unfortunately, Holley hasn't made a Dual Sync for my Chevy 250 inline 6 yet.


Take a look at the description of that video as I've included a Video Index and part links to the couple items I used. Here are the steps from the video recapped for easier reference:
  1. Remove the distributor and confirm you are using a smiliar 4 pin module version. Ours was sourced off eBay 7 years ago. Here is a similar distributor, with the same part number from the same seller.
  2. If so, lockout the mechanical advance. You can weld it, secure it with a screw or make/buy a distributor lockout plate
  3. Secure the vacuum advance rod or reluctor adjustment tab. For simplicity we used a Speedway HEI Manual adjustment knob, which allowed for easy rotor phasing later on.
  4. Set your engine timing to your desired reference angle, 10° higher than the maximum timing you'd want your motor to see. If you want 36° at wide open throttle, make your reference angle between 46-60° BTDC on the compression stroke. For the video and these instructions, your timing is set to 46°.
  5. Fully seat your distributor with the housing in the desired position and your rotor pointed toward the #1 Spark plug terminal on your distributor cap.
  6. Mark the edge of your distributor housing with the location of the brass contact of your #1 Spark Plug terminal.
  7. Turn the distributor housing to line up the closest reluctor magnet with the pickup.
  8. Secure the distributor.
  9. Use the vacuum advance knob or rod to adjust the reluctor to ensure the rotor is pointing near the most counter-clockwise point that you marked on the housing. This will ensure when your engine drops from 46° to 36° it will be partially in front of the brass terminal.
  10. Once you're happy with the phasing, check it by moving to your engine timing to it's mid range. If you crank at 15° and go wide open at 36° then move your engine to 20°. At 20° your rotor should be close to perfectly centered in front of the brass terminal of your #1 spark plug.
  11. Hookup your magnetic pickup wires to the green/purple crank trigger wires of your Sniper EFI System. We used this MSD HEI Module Bypass Cable which allowed us to use the connector on the Sniper harness and plug right into the magnetic pickup connector.
  12. If you're using the Holley Coil Driver, hookup its grey wire to the Tach terminal on the distributor, or to where the module plugged in on terminal "C".
  13. The Holley Coil Driver requires a ground connection, white wire to the Sniper main harness and a pink accessory 12V power connection. We spliced the pink wire into the pink wire supplied to the main harness of the Sniper EFI system and it worked perfectly.
  14. Pull the fuel relay or prevent fuel delivery somehow.
  15. Open your ECU config in the Holley Sniper EFI software. (via CAN/USB dongle or manually via SD Card)
  16. Under Engine Parameters, Set your Ignition Type to "Magnetic", Reference Angle to "46°", Minimum Signal Voltage to "0.65" and Filtering to "High". Take the opportunity to ensure the Base Timing Table is at least in the right ballpark for your engine. Save the config.
  17. Upload the new/saved config file to your Sniper ECU.
  18. Set Static Timing Check to 15° and turn the key. With a timing light your engine should crank near 15°. If it cranks within a few degrees, make the small adjustment to your distributor housing to set it at 15°. Try cranking again to ensure it is now locked at 15° during the static timing check.
  19. Re-install the fuel relay or activate your fuel system.
  20. Set the Static Timing Check to 15° again, and start the engine. With the engine running, ensure it sits at 15°. Again, if it's very close but could be better, make the small couple degree adjustment.
  21. Increase the engine RPM to verify the static timing holds. It won't, so in the Ignition Settings (handheld), try increasing the Inductive Delay to "0.100" and power cycle the engine. Re-enable the Static Timing check of 15° and increase the RPM again. Our vehicle's timing moved to approximately 16° at 3500RPM, which is an acceptable amount of movement. You may be able to fine tune the Inductive Delay to get it even better.
  22. Clear the static timing and take it for a drive, if you've been rapidly cranking and starting/stopping the engine, you may want to give it a good run to charge up the battery, at least that's the excuse I used to get out of the house.

Obviously these instructions, and the video couldn't cover every little aspect of this procedure but I think it'll steer a lot of people in the right direction. Keeping in mind the right direction may to go with a supported method of timing control. Ian