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Alternator Suggestions ITT

J

jonward786

Member
I had a lovely experience today driving from san jose to san luis obispo. after my recent overheating problem i was driving with my eyes fixed on the temp gauge the entire time. then i happened to glance over at the tach and noticed it was reading 1500 rpms. "that's strange" i thought, considering the fact that i was going 70 mph with a C4. then i watched as it slowly went even lower, 1300, 1100, 900..all the way to 0, yet the car was still humming right along like normal. then i noticed the other gauges started doing the same thing, all their needles slowly going down to zero.

and then it happened, all electrical power gone from the car and engine died. so i rolled to the side of the road, got a tow on the way with AAA, and waited. a nice CHP stopped by to see what was going on and stayed with me until the tow got there (30 minutes later) and we sat in his cruiser and talked. He said gradual electrical failure like that most often means alternator. The tow truck driver agreed when i explained to him what had happened.

So long story short, it seems i need to replace my lovely stock alternator after 42 years in service. What do you all recommend. Something easy to install preferably that wont involve rewiring. I heard stock alternators provide something in the ballpark of 50 amps? i have a bit of a sound system in the car, and ive heard its a good idea to run a more powerful alt. to accommodate things like that. Thanks in advance for your advice
 
I'd do a little testing. Put a voltmeter on the battery...you should see a little more than 12v if it's not dead (and it's probably dead). At idle, you should see ~13-14v at the battery, so check that too. I'd also take the alt and regulator and have them tested. Could be that the battery is total junk and cannot support a load for a long period of time anymore.

There's no such thing as a bolt in alternator upgrade...the stock alternators are so low output that upgrading to a modern unit without upgrading the wiring makes for a fire risk on wheels. The factory charge wire *will* melt.
 
You've got alternator issues for sure. You can probably let the car sit for a day or two and it will fire back up. I'm interested to hear the alternator choices as well as I'm gonna upgrade in the near future and am running stock wiring. Driving a car with a dead alternator is a lot of fun. You ought to try it sometime. If it happens again always keep the engine revving. It goes something like this: Foot on throttle maintaining some rpms. Not many, 1500-2000. d,n,d,n,d,n,d,n.......It's much easier with a manual transmission.
 
FFS Jon, lol. Why can't you seem to make it home or back without issues?

One option is a GM 3-wire or 1-wire alternator. The 3-wire requires minimal rewiring, and the 1-wire is pretty much bolt-in. Not a huge upgrade, but more output than the stock externally-regulated setup.

A Ford 3G alternator is one of the better options, but requires some rewiring.
 
It is possible that i just have a bad ground? I grounded the alt to the same place i grounded the negative terminal on the battery, to the front passenger side of the block. thing is, i dont think i scraped off the paint for good contact before i grounded. hmmm
 
As Gotstang suggested get the other parts of the system tested while you're down, just bring the batt. into any parts store and leave it for them to put a full charge on and do a load test, might take a day but will rule out the battery at least.
Make sure you also have an engine block to chassis/body ground also (my '67 had a braided metal strap from the pass. head to firewall) besides just alt/batt to block and yes, scrape off the paint to get a good ground, put some dielectric grease there to avoid rust.

If you still want to upgrade your amps for stereo, etc. I chose a fairly easily option of stepping up to a mid '70's large case 1G 100A. Same wires just need to splice the ends of the 3-4 wires ( +, -, STAtor, FieLD) that go to the alt. itself for the type of connection. I went 1-2ga. up in wire size at the same time, this alt. also uses the same exact VR as my stock 45-65A small case 1G alt. did. It is a little larger so I had to tilt my lower mount down slightly and get a ~1" longer belt.

This upgrade worked flawlessly for ~1yr. until I tore the car down for a rebuild, you don't need to give it a rev to 'excite' it at idle either, you have full power at idle. A nice upgrade for the stereo/amp/brighter lights/driving lights with relays that I'm installing and room to grow.

Just an option if you don't want to change too much from the stock setup, few people noticed it wasn't the smaller stock alt. at shows. Here's some pics before teardown, the wires will be cleaned up and covered as well as a rubber cap to protect the + terminal from getting touched with a wrench by accident on reinstall:

Stock small case 1G 45A-65A.................................Large case 1G 100A
Alt100Avs65Ab.jpg


Alt100A.jpg


Alt100Ainstalled3.jpg


Alt100Ainstalled2.jpg


Jon
 
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