Wow one electric fan...

[1974dodgecharger]

Cause my voltage guage t swing from 12 volts to 14 volts when on.  When I accelerate she hits 14 and i idle she does 12 volts.  Before she was doing 14.4volts or so.  This is only one pusher fan doing this...this must mean a alternator upgrade, especially if i do 2 puller fans to replace mechanical fan.

[WHITE AND RED 69]

Yeah whenever more electrical additions are added it's time to beef up the charging system. 

How is it cooling? If its good I wouldn't add any more electric fans. Try and stick with the mechanical and the pusher fan.

[Pete in NH]

It's real easy to get on the trail of one change leads to another. The stock alternator on a 74 should be the newer squareback type which should be good for 60 amps max. I'd be careful if the wiring is stock and 40 years old about going bigger on the alternator without doing some rewiring, especially if you're still using the stock ammeter along with that voltmeter you mentioned.

[Paul G]

It's real easy to get on the trail of one change leads to another. The stock alternator on a 74 should be the newer squareback type which should be good for 60 amps max. I'd be careful if the wiring is stock and 40 years old about going bigger on the alternator without doing some rewiring, especially if you're still using the stock ammeter along with that voltmeter you mentioned.

Absolutely! Just upgrading the wiring will improve the low voltage condition without replacing the alternator. Installing a more powerful alternator without replacing the wiring just makes for a bigger better electrical fire. Not something you want I am sure. 

[1974dodgecharger]

Well i did the bypass ammeter setup with 10 guage all around the electrical setup.  Now i think I should of done 6 guage, man.  Now i remember why I didn't get a bigger alternator just too expensive right now vs other car priorities.

[Paul G]

Have you replaced the wire from the alternator and from the battery (start relay) to the under dash connections yet? Those wires will have burnt terminal ends in the bulkhead connector. Guaranteed, unless they have previously been replaced..

[myk]

Eh, it's wiring that's almost a half-century old.  For safety and performance the best thing you can do is rewire the whole car.  Yes it's expensive and a relative pain-in-the-butt, however it's the only way you can just about guarantee your electrical system and any modifications you want to throw at it.  No more by-passes, splices, patches, shunting, and more importantly driving around with a fire extinguisher and staring at your ammeter/voltmeter, wondering if today will be the day that the fires of hell manifest themselves in your car...

[1974dodgecharger]

Paul,
Yeah all upgraded the previous wire was frayed and horribly thin and Ty rotted outl.