Alternator question

[Deeeno]

I have a 65 barracuda formula S and just put in a 360 magnum . I put a new alternator on it when it had the 273. Now it seems to not charge enough do I need to put on an alternator that puts out more than the 60amp? I noticed that the Dakota with the same engine has a 136 amp alternator. I drive it and after a while the battery seems low and I had to jump start it. And advise ???

 

[67Dart273]

Well believe it or not this is "not that simple." Is this magnum swap carbureted or fuel injected, and do you have added electrical stuff such as fuel pumps, electric fans, etc? In other words more details on the deviation of the electrical system from stock, and added accessories

The factory original alternator would have most likely been 37A. As old as these girls are, "any bodies guess"

Also Some years can have damage to the ammeter/ bulkhead connector circuit, which is an issue, AND the alternator may not be putting out what it should, ---1 or more bad diodes, or other problems, OR EVEN SIMPLY a slipping fan belt

Start by going over to MyMopar and download the factory manual OR AS close as you can get--you may have to accept a Dart manual rather than Plymouth, and some manuals won't have the special wiring for Barracuda/ Rally dash..
Service Manuals – MyMopar

Also download the more simple 2 page aftermarket diagrams, which are often not as detailed or complete, but can be easier to follow than factory
Wiring – MyMopar



Also go over to MAD electrical and read the artical about ammeters/ bulkhead connectors, which EVEN IF you do not perform that mod, it gives an overview as to "what."

Catalog

The other danger is, that if you put something as large as a 60A up against the stock wiring YOU RUN A RISK of tearing up the ammeter/ bulkhead connector. On the later cars, there was a factory? dealer? mod known as "fleet / police/ taxi" wiring for the optional 65 A alternators which ran the ammeter wires in through the bulkhead in individual grommets-- thus not endangering the terminals in the bulkhead connector

Troubleshooting steps:

1....Test the battery, make sure it is fully charged, and of adequate capacity
2.....Test the charging system, making sure that it is putting out rated amperage/ voltage
3......Do a "survey" of the car and determine system loads

 

[Professor Fate]

I'll assume for the moment that you converted the Magnum to an LA style TC/WP and front drive since you are using the same alternator you had on the 273. So, one other thing to consider is that the pulley system you used on the conversion are not the same as your old drive ratios, and may now be underdriving your alternator. Compare your current pulley diameters to your old setup. You may need to use a different (larger) crank pulley or a smaller alt. pulley. These drive systems are best swapped as a complete matched setup.
P.S.- When you swapped engines, you DID make sure to reconnect all of the engine ground straps, right? Good, solid grounds?

 

[Joey4speed]

I wouldn't increase amperage just yet.
You may fry some old wiring, if it's original.

 

[Syleng1]

Also make sure you have a good ground between the engine and fire wall, fire wall to battery and battery to engine.
Voltage regulator- newer VR style or still have the older points style that is original to the car (black box)? Those go south very easily after engine swap and missing ground. Don’t ask how I know as recently as a month ago.

 

[67Dart273]

I'll assume for the moment that you converted the Magnum to an LA style TC/WP and front drive since you are using the same alternator you had on the 273. So, one other thing to consider is that the pulley system you used on the conversion are not the same as your old drive ratios, and may now be underdriving your alternator. Compare your current pulley diameters to your old setup. You may need to use a different (larger) crank pulley or a smaller alt. pulley. These drive systems are best swapped as a complete matched setup.
P.S.- When you swapped engines, you DID make sure to reconnect all of the engine ground straps, right? Good, solid grounds?

EXCELLENT idea