What voltage should I expect?

13.8 volts is plenty good…find something else to worry about.

Alan
N.J.

 

yes 13.8 volts at the plug is fine, remember there will be a voltage drop through the system, you should be checking the voltage at the battery, put a meter across the battery terminals and see what you have there.

 

Ditto what 26 St said, that voltage drop is normal when checking at the lighter socket, always measure like said at the battery only for a true reading of system performance. Expect about 14.2 volts or so at a fast idle at the battery.

 

+1 -- it's only much newer cars that get up to 14.2~14.4V.

 

if you have access to an AMP clamp tester, put it on the battery cable with full electrical load and see if the alt is putting out should be close to what the AMP rating is for your alt.

Ferrari uses the frame as a ground so there will be a voltage drop back to the battery; I ran a cable from engine block to battery i get better starter response with lower amps. after running the cable, a lot of little electrical Germinals stop popping up.

 

All Ferraris from the Daytona and earlier have a heavy braid from the battery negative to the block and another from the bell housing to the frame. This helps keep that voltage drop to a minimum.