i have a 1928 dodge senior six street rod which is all mopar under the sheetmetal, 318,904 83/4 rear. my problem is added a/c unit from southern air which is supposedly pulling35amps all by itself. current alt. is not powerful enough. puts out 14.2 volts ok, but only63 amps.with lights and a/c and am/fm radio on car will cut out
just too much of aload. couple of things i have been told so far is thatamp meter from donor dodge ,69-70 charger will only handle approx.35 amps thru it before frying it. this info came from several good streetrod parts suppliers and i
dont see any reason to doubt them. a couple of suggestions for curing said problem so i can run 100 amp alt. have been swap gauge for 1 marked 60-0-60 gauge currently reads 40-0-40 when and what where these used in? other possible solution was to run 2 4awg rated wires from b post on alt. directly to battery ,giving electrons easier path to follow. suppoedly gauge will flicker as it charges or discharges, but will keep from frying gauge. by the way am using cluster that came fom 69-79 charger w/ 318 and auto w/a/c... doner car only had 53 amp. alt.also noted talk about hooking up 2 field alts. i only have one field connection plugged in was told by alt. repair shop to use either one. should i hook up second one and if so why? sorry if this is too long a note, will try to keep it shorter next time tahanks for any help anyone can provide in this matter.

You're better off to bypass the amp gauge all together. Run an aftermarket volt gauge. Amp gauges are in-line gauges and really restrict the total amount of current you can flow. Just bypass the gauge. It's safer that way anyway, plus a volt gauge is just as good. You'll get more/better power flow from your alternator to your battery.

How can an a/c system pull 35 amps? Only electrical components is the clutch on the a/c compressor, and I can't see that taking nearly that much current. Nor would your fan motor take much either. I could not tell you how to use up 35 amps on an a/c system.

Why would you want to run 2 4awg wires instead of a single 2, 1 or 0awg wire? Your current alt should be more than enough for your setup. The bypass will help free up some power. Try that and go from there.

And your car should not cut out from too much of a load, that part makes no sense to me. If there's too much of a load, the electrical system will just suck current out of your battery if the alt can't supply enough. You'd have to drive until the battery drained until it'd die.

thanks for such fast response, a/c system has 2 fan systems 1 inside car, and 1 outside under remote condensor ,plus a/c clutch. was given this amp. number by manufacter of a/c system. custom built for this application.
thanks

Running a heavy wire from the alternator output post to the battery or starter relay of there is one will bypass the ammeter and support running a 100 A alternator. One 6 guage wire should be more than enough. Its recommended to splice several inches of fusible link in the 6 guage wire to protect the system from serious shorts. 10 guage fusible link should be about right and is available at auto electrical stores. The ammeter wouldn't work with this change. An accessory voltmeter would be a good replacement.

Another and potentially bigger issue is why the car "cuts out" with high electrical load from the AC. Even with a small alternator it should run OK for quite a while on battery power. OE Mopar's were orignally designed this way; they would discharge at a stoplight and "catch up" running down the road. It sounds like the AC may be on a weak or overloaded connection on the original donar car's wiring. Original AC would draw +/-15 amps so if you're pulling 35 that's too much for the original wiring. I'd check all connections and consider running a dedicated power supply for the AC with 10 guage minimum wire from the starter relay or battery with an appropriate fuse. 35A sounds like a lot for AC but I guess the manufacturer knows

The 2 field upgrade will help and may be necessary depending on what alternator you choose. Consult a wiring diagram for a 70 or later Mopar as a guide. (I don't have access to one now).

Good luck.

I agree, there is some issue with the car cutting out.
I did an a/c upgrade and just found I could not start the car after shutting it down because it drained the battery down while running instead of charging.

What I did to fix it was go to the square back alt for an 89 m-body. A newyorker or dippy, but not the cop car alt.
These put out around 74-78 amps and was enough to keep the battery charged with 2 electric fans, and the a/c system going full blast.

For the 318, you need the longer swing arm. I got the 10 dollar gm chrome swing arm that they sell in every parts store.
You need spacers to get the arm out far enough. I got some from the a/c system I put in, but I saw the other day that lowes has them in those drawers in the hardware section.

Then you hook up the single field and ground the other one. It doesn't matter which one you use and which one you ground.