Quote Originally Posted by hegill View Post
I know that the Cranking Timing according to the Holley software is 15° and that I should ensure that the timing when used with a timing light and cranking without starting the engine should match this value.
Correct: http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Step #4)

What I don't understand is:
1) What's the timing supposed to be at idle with no advance on the Holley EFI setup?
There's not "no advance" in the Holley EFI software. With a GM HEI & Ford TFI, simply set the Ignition Reference Angle to 10° and forget about it (it's not your idle timing).
http://www.masterenginetuner.com/top...all-fails.html (Crank Reference Angle Importance)

2) In the manual for the 3.5" handheld it shows a picture where the ignition timing at idle is 20°, but then says that for the idle timing typically anywhere from 18 to 34° is used. Do these values represent the Static Timing plus the advance that the ECU adds?
No, the Static Timing synchronization feature (temporary EFI software tool) is exactly what's entered. And the ECU controlled timing (Static Timing synchronization feature off) is exactly what's programmed in the Base Timing Table. If you're referring to static timing as the initial timing (no vacuum advance), then you must specify that because Static Timing means something different in the Holley EFI software. It's a temporary EFI software tool for synchronizing the ignition timing.

3) How can I determine what the actual timing is at idle with no advance, if this is a combined value?
Believe the timing light above all else, it's always the real timing (if there's a discrepancy).
When finished, the timing as viewed on the laptop, should match what you see with the timing light, at all RPM.
Once the ignition timing is fully synchronized, the Timing Table can be tuned for each application.

4) If the ignition advance values need to be changed, is that done in the base timing graph or Base Timing Table or somewhere else?
Once the ignition timing is synchronized, all timing tuning changes are performed in the Base Timing Table. The Timing Graph is just an EFI software visual aid for the end user.

The ECU needs an Ignition Reference Angle, so it can control the timing. (10° Ignition Reference Angle is correct for GM HEI & Ford TFI. The GM HEI & Ford TFI distributors are installed at 10° Ignition Reference Angle, but they're operating one crank revolution ahead, so they're retarding a lot. On a high RPM race engine, it's best to keep the amount of ignition retard (occurring from such an advanced reference angle) to a minimum, so it's not used on expensive race engines. Of course, timing accuracy is better with a crank trigger.)
http://www.masterenginetuner.com/top...all-fails.html (Crank Reference Angle Importance)

Example: An EFI distributor doesn't have a centrifugal advance & vacuum advance mechanism; that's all locked out if converting an old carbureted distributor to ECU controlled EFI ignition timing. So the initial & vacuum advance is combined in the "Idle", "Cruise" & "Deceleration" areas of the Base Timing Table:

Click image for larger version. 

Name:	EFIFuelTable_zps7d2b8421.jpg 
Views:	214 
Size:	93.1 KB 
ID:	9506