Reply to "Engine timing with MSD iginition"

Dennis,

Have you tried using the timing light yet? It should be a non-issue.

My advice is that you do not need a timing light. Start by connecting the vacuum advance to ported vacuum. Leave the vacuum retard disconnected. Loosen the distributor locking bolt enough to allow adjustment. Start the motor, let it idle, once up to operating temp, slowly rotate the distributor in the advance direction. (clockwise). As you rotate the distributor, the idle speed will increase, continue to slowly rotate the distributor until you just reach the point where the idle speed stops increasing. This is the ideal advance setting for idle, and it will be significantly different than the specified setting from Ford. Ford’s setting was derived to meet emissions, it never was an ideal setting. If you’ve modified the motor in any way, the oem setting no longer applies anyway.

This new setting is more efficient, your motor creates less waste heat, and therefore overheating at a stoplight is less likely. Fuel consumption will improve. Drivability, low rpm power & throttle response will all improve.

The full advance setting is likely to be off now, but how often do you drive at 4000 rpm or higher? The centrifugal advance will eventually require re-curving to something like 10 to 16 degrees in by 3000 to 4000 rpm. It all depends upon your motor’s state of tune, the fuel you use, etc. Full advance is best determined on a chassis dyno.

When twisting the distributor, as Julian wrote, there is a spot where further twisting results in no change in idle speed, if you continue to twist the distributor the motor would eventually begin to buck. You want to set the distributor at the point where the motor just reaches its highest idle speed.

Afterwards you will need to re-adjust your idle stop to set the motor for an idle of about 1000 rpm, and re-adjust the needle jets for highest idle speed too.

Rather than adjusting these settings using the tachometer, you can just as easily set them with a vacuum gage attached to the intake manifold. The ideal ignition setting and the ideal idle jet setting will result in the highest intake manifold vacuum as well.

There are circumstances where the setting derived in this manner may have to be backed off a bit, but this is a good starting point. The problems you may encounter are engine knock under heavy load or difficulty cranking the motor. The first fix for these problems is to connect the vacuum advance to manifold vacuum rather than ported vacuum, then readjust the distributor & carburetor settings in the same manner as the first time. You’ll never know if this is necessary until you give the first method a try.

Your friend on the DTBB