69 GTX Idle Charging issue
 

I have a completely restored 69 GTX 426 Hemi -

At idle the car will not put a charge back into the battery.
I have an optima red top battery (brand new).
My mechanic and I have checked the alternator and it is working fine.

Both mechanics I use tell me this:

All Mopars from the 60's and early 70's had this as a known issue.
That wheel doesn't spin fast enough at idle (or isn't the proper size) to charge the battery.

So if it doesn't keep a constant 11 volts - my stereo starts cutting in & out.
Then at night with the headlights on - in stop and go traffic it puts a serious drain on the battery.

Once a month I have to put the battery on a trickle charge to be safe PLUS carry a battery pack in the trunk to jump start myself.

My mechanics are not novices - one has been building engines since the 50's with his dad and builds race car engines for a living. The other has been a mechanic since the 70's and raced as well.

I am stumped - has anyone else gone thru this and what have you done to cure it ?

Thank you in advance

The only thing I can think of is that you may have a short that is causing the battery to drain faster then it can charge at idle. If I were you I would look into that.

Put a LARGER crank or a smaller alternator pulley on !

Both mechanics are telling you this ? I am not saying that they ARE like-this... but there are alot of people that are hacks.

ALL Mopars are like this ? .... that is simply not the case.

for one thing you need more than 11 volts //// i would check the voltage regulator and make sure it is GROUNDED good to the frame if it is on the fire wall and make sure it is the (right one) or if its internaly in the alternator i would get a new 75 amp one ,,, take the alternator to a auto parts store and have them check it to see if it is putting out enough amps while (off) the car then we can see where your at ok :D Plus what is your idle rpm

Thank you for the replies:

My idle is 800

I will continue to isolate this problem piece by piece.
It has driven me crazy for close to 3 years.

do you have the mechanical regulator or an electronic? the mechanical regs are adjustable. have you tried grounding the body to the battery?

do what was already suggested, especially the grounds. also, if you have a bad diode in the alternator, it can cause a low output at idle but still charge at higher rpms.

The new BLUE reg is a better piece.