figured i'd ask , just in case . 1972 dart 318 , stock . daily driver . alternator went . i had one sitting around here that some cool old school mopar man gave me years ago . that was tested good for my application , at a autozone ,recently . and matches up almost perfectly , but when i went to put the belt on , the belt was harder to put on . i noticed the pulley where the belt goes in was a bit larger than the old one . the belt fit great and is not too tight . but i was just wondering . can the diameter of the pulley cause any difference ? anything to worry about ? it's already on and its too damn hot to start over . do i need to swap the pulleys ? have i been out in the heat too long ?
1972 dart alternator pulley shaft question
- Thread starter moparjon
- Start date
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Larger diameter pulley will not charge as well at idle. Otherwise it will be ok.
How are you putting the belt on?
You should be able to loosen the tensioning bolt and rotate the alt inches out of the way then pull it back up to tighten the belt.
How are you putting the belt on?
You should be able to loosen the tensioning bolt and rotate the alt inches out of the way then pull it back up to tighten the belt.
yes like that . but it starts out rather snug because of the larger pulley . the tensioning bolt at its loosest point all the way , is already kinda snug until you get the belt around the pulley and into the groove , then i lift up and tighten the tension bolt , then tighten the top bolt .
test driving it , its going ALL the way to the charge side anything past idle , and mostly staying there . maybe the battery was really drained , but after 10 minutes of driving it has not moved . i am gonna test with the multimeter , i don't want to cook the battery . it came down to normal driving with the lights and a/c and heater blower on . went right back to all the way if you turn them off . not sure if i am overthinking it .
battery showing 12.65 on the volt meter engine off . stays the same running at idle , when i put it up to fast idle on the carb , it's reading about 13.10 ish . full throttle tops out at 13.35 but the alternator gauge at idle was fine , then went all the way to the charge side again at fast idle . it definitely didn't do that before changing the alternator today . it would go a little to the charge side normally on startup and then quickly back to center . i don't know how long i was driving it with the bad alternator , but it cranks real good and starts right up . any thoughts ? anything i should be checking ? anything to worry about ? i need the car in the morning .
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67Dart273
Well-Known Member
13.3 is low, but it might be the battery is still low. Charge it up if you can or run it awhile and recheck. With battery "up and normal" AND ENGINE WARM (the VR is temp compensated) battery should run 13.8--14.2 +/- a couple of points
ok , i will do that , something i forgot . before replacing the alternator i disconnected , cleaned up and reconnected the battery ground where it goes through the front by the radiator . also , i removed the ballast resistor on the firewall , cleaned that up and reinstalled . both of these did not change what the gauge was doing ( staying at slight discharge ) . but is there any concern there ? would it do what its doing if the ballast isn't grounded to the firewall correctly ?
sorry if i am not making sense , its been a long day in the heat and i didn't stop to eat yet .
thanks for everything , i am gonna take it out for a drive .
ok i just took it out for about 20 miles , lights on though cuz it got dark , rechecked showing 12.73 at idle , 13.43 to 13.45 at fast idle , stayed same if i open the throttle full . so its a little better , but not much .
67Dart273
Well-Known Member
You might want to check both at the alternator output stud and at the battery to see if you have voltage drop. Also, what kind of load is on the system, IE do you have big pump, water pump/ electric fans etc, or the alternator may have a problem and is not outputting rated current.
Possibilities:
Battery still low or has a problem
Alternator has a problem and only partial output, or just is a small unit
Voltage drop in the charge wire
Excessive system load, AC/ lights/ pumps/ fans/ etc
Possibilities:
Battery still low or has a problem
Alternator has a problem and only partial output, or just is a small unit
Voltage drop in the charge wire
Excessive system load, AC/ lights/ pumps/ fans/ etc
sorry to ask , but , exactly how do i do that ?
The ballast resister does not use a ground. It bolts to the firewall but all the current flows from one terminal to the other and only effects the ignition system.
There are a number of issues you have identified.
- Charge indicator going all the way to the right.
- Alternator belt / tention
- Voltage of battery / alternator
- Charge indicator, typically the indicator will show charge to about the first right tick after starting, then within a few minutes if driving will settle in around the center. If the battery is drained it will stay to the right a long time ( I had drained my 67 dart battery till it would not start the car. Jumped it and drove it for about 30 minutes. The charge indicator stayed to the right the entire time. I ended up putting the battery on a charger over night, next day back to normal) try putting the batt on a charger over night, auto parts store can do it for you if you bring the battery to the store. There is a possibility the battery is failing and taking more current to charge then normal.
- Your belt might be too small, or the adjusting bar is in the wrong hole. On my 273 the adjusting bar does not need to move only the bolt that goes through it and to the alternator needs to be loosened and the pivot bolt loosened a tad to adjust the alternator. The alternator should sit midway through the adjuster travel slot
- Your engine off battery voltage seem about right at 12.75 ish. Your engine running battery voltage at about 13.5 is ok too assuming the battery is not fully charged.
I am making assumptions here that your car is stock and no added loads.
If your alternator adjusting bar is bolted in this hole it is not in the correct location.
This is on a 67 273 and yours has slightly different brackets so it may not have that hole to mount to.
The adjuster in my case should be on the bottom bolt.
In my case the alternator could not be rotated down enough due to the adjuster bar hitting on the alternator. When it is in the correct location the alternator rotates freely down with the adjuster bar firmly attached to the water pump
This is on a 67 273 and yours has slightly different brackets so it may not have that hole to mount to.
The adjuster in my case should be on the bottom bolt.
In my case the alternator could not be rotated down enough due to the adjuster bar hitting on the alternator. When it is in the correct location the alternator rotates freely down with the adjuster bar firmly attached to the water pump
With engine running...
Measure from battery ground to alternator out put and then measure from battery ground to battery positive terminal.
Another way is to measure between battery positive and the alternator post. This should show very low voltage like 0.5v or less
When comparing between battery 12 volts and alternator voltage 12.5v the difference is the voltage drop 0.5v (the numbers are for example only)
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