I know there's a few post on here about base timing, but my question is why my car with the EST unplugged has a base timing of 4 BTDC, and with the EST plugged in it jumps to 12 BTDC. Any help would be appreciated.

 

Because with the connector unpluged you are at the advance set by where the dist is in the block.
Once you plug the connector in the computer then has control and advances the spark ( as it should ).
That is why you have to unplug the computer when setting timing because you will be fighting against the computer

 

i was just wondering if it was correct cause 12-14 degrees seems like alot, but thanks.