12 volt conversion

[naturalthud]

Deve-

Your website is great! So much useful information, well organized and the photos are great. Do you have information on converting from a 6 volt to 12 volt system? It would be great if you had a write up and/or a Farm It Out kit for this mod.

Thanks for all you do.

naturalthud

[Deve]

There is a need for a kit alright. I just haven't gotten around to it yet. But for those who need it now.. There are two articles on the site that together should help explain what you need. They are:

http://www.devestechnet.com/Home/Native12VUpgrade

http://www.devestechnet.com/Home/ADWiringSystem

The nice thing about 12v upgrades is how easy it is for the most part. Get yourself a 42 amp 3 wire alternator. The reason for 42 amps is your ammeter is rated for 50 amps so to keep the system balanced, go with the 42 amp. This does not require a regulator at all. The first article above explains how to hook it up. The next thing is get the Zener Diode suggested in the same article for your 6 volt fuel gauge. Next get a 2 ohm Ballast Resistor for your ignition system. So the wire that goes to the positive side of the coil gets a Ballast resistor in between that wire and the coil. Lastly, change out all of your light bulbs. The part numbers for everything mentioned above is in one of those two articles.

If you REALLY want to make your system nice, upgrade to 12 volts and then go with HEI system for Ignition. No need for Ballast resistor and a very nice running engine. Happy to help as you do it. Just ask away!

[naturalthud]

Thank you for the response. I am switching over to 12v to support a HEI ignition. Do you have any suggested performance specs for the battery?

[Deve]

You do not really need anything special for the battery with a 42 amp alternator. Just a good quality one that fits in the box. I purchase my battery from NAPA because they are close. I get the premium one with at least a 3 year warranty.

[naturalthud]

Any recommendation for the alternator? I have been shopping around. No luck what so ever finding an alternator that is 42 amp 3 wire. The closes alternator I have found is a 45 amp 1 wire from Autozone.

[Deve]

http://www.rockauto.com/en/moreinfo.php?pk=38314&jsn=447

This is the 1977 Alternator of choice which is 42 amps, 3 wire and the part number is REMY 20040. The cost is about $50 at Rockauto. The main idea is to keep it under 50 amps so you do not have an imbalance with the Amp Meter which is rated for 50 amps tops.

[naturalthud]

Thank you! Alternator ordered!

DS

[DBCooper]

I put a 50 amp 6 volt alternator with an internal regulator in my 6v system. Any concerns with that set up? Has worked fine for 3 yrs.

[Deve]

Not that I know of. That is a pretty common upgrade when staying with 6 volts. It makes the system much more reliable than the old generator/regulator setup.

[baldilocks]

http://www.rockauto.com/en/moreinfo....=38314&jsn=447

This is the 1977 Alternator of choice which is 42 amps, 3 wire and the part number is REMY 20040. The cost is about $50 at Rockauto. The main idea is to keep it under 50 amps so you do not have an imbalance with the Amp Meter which is rated for 50 amps tops.

I know this is an old thread but it needs an update. I'm going from generator to alternator and prefer to retain my ammeter. I ordered the Rock Auto product, advertised as 42 amp remanufactured unit. when the unit arrived ths spec sheet indicated it was remanufactured to 63 amp specs and the pre shipment test record showed it actually peaked out at 79 amps. I called the tech support number on the spec sheet and talked to the DelcoRemy rep. He said all of the 20040s are remanufactured with 63 amp components and most actually crank out higher. I returned the alternator to Rock Auto and had to pay for return shipping. Didn't matter to them that the product was not as advertised. I ordered a remanufactured 20038 from a different vendor which is supposed to be under 50 amps; we'll see... If this one doesn't pan out as advertised I'll bypass the ammeter and install a clamp on voltmeter. Caveat emptor, remanufactured alternators don't necessarily match original specs.

Steve

[Deve]

I assumed Delco Remy (of all people) knew what they were advertising. Rockauto wasn't at fault (other than their return policy when something is not as advertised!). They are getting their info from the manufacturer. Shame on them! In any case, depending on how dedicated to your precious ammeter you are, and I personally like it enough to go to some effort to keep it, here are a few solutions that allow it to stay put no matter the size of the alternator. Each one has its drawbacks but until we hear back about your efforts to get a <50 amp alternator, here are the choices I know of:

1) 50 amp Automotive Circuit Breaker like this one: https://www.summitracing.com/parts/prf-80042
Disadvantage: They work on thermal so they have only a limited number of 'trips'. This number is a large number (not sure how many times you can trip it) and if you let it sit there and just do its job, it will be good until it's actually needed.

2) 50 amp Fuse Holder like this one: https://www.summitracing.com/parts/rra-fs69140
Fuse: https://www.summitracing.com/parts/bss-agc50

Advantages: No number of trips. It's a fast blow fuse! Mount near the starter and connect your 10 gauge wire that feeds the entire system to it first, and the system is protected from any spikes. Fuses are available in 40 amps as well for those who really want to protect the wiring.

3) Fusible Link like this one: https://www.summitracing.com/parts/pco-5551pt
This is the way I chose to go. Only because the automotive industry went that way. I have since decided option 2 above is a better idea. Just because the entire automotive industry says it, doesn't mean it's the best idea. Sometimes, like in the case of a massive 50 amp overload things happen so quickly (in the low milliseconds) that the fusible link doesn't burn fast enough to protect the wiring. I have actually seen this phenomena myself.

As we learn more from firsthand evidence, we will always come here to keep people apprised of what we find. Almost all alternators available these days spool up higher than 50 amps so what you need is an alternator that is incapable of going higher than 50. That could be very hard to find. (Especially in Gloss Black so its not seen easily for you semi purists out there). Please let us know Steve what you come up with!

Keep in mind, most people (well over 90% in my estimation) just throw a high amp alternator in their ammeter equipped truck and just blow off the danger. They might go their entire lives without a problem. Don't be one of those people! Ask yourself how does your luck run?

[AD_NAPCO]

Hey Deve,

I'm digging in to the research for the 12V conversion for my 55 first series 3600 and I'm looking at options. I really dislike the look of the more modern alternator in our old trucks, and so I'm considering a Powermaster PowerGen alternator so I can retain the stock look. It seems though that they only sell a 1 wire alternator with an optional lug for a generator light. I have noticed that you generally specify a 3 wire alternator in your tech articles. For our old trucks, is there a particular reason you prefer the 3 wire system? It also seems that most of the vendors sell 12V alternator harnesses that are designed for 1 wire alternators. I also like my ammeter, and after reading the above post, I'll be going with option #2 above.

Thanks,

Josh

[baldilocks]

I know this is an old thread but it needs an update. I'm going from generator to alternator and prefer to retain my ammeter. I ordered the Rock Auto product, advertised as 42 amp remanufactured unit. when the unit arrived ths spec sheet indicated it was remanufactured to 63 amp specs and the pre shipment test record showed it actually peaked out at 79 amps. I called the tech support number on the spec sheet and talked to the DelcoRemy rep. He said all of the 20040s are remanufactured with 63 amp components and most actually crank out higher. I returned the alternator to Rock Auto and had to pay for return shipping. Didn't matter to them that the product was not as advertised. I ordered a remanufactured 20038 from a different vendor which is supposed to be under 50 amps; we'll see... If this one doesn't pan out as advertised I'll bypass the ammeter and install a clamp on voltmeter. Caveat emptor, remanufactured alternators don't necessarily match original specs.

Steve

I finished my conversion last summer. The 20038 I ordered didn't come with a spec sheet so not sure how many amps it actually cranks out. I opted to keep the ammeter per option #2. I ordered a waterproof 50 amp breaker from Amazon. It's the kind used on boats to protect trolling motors. I mounted the breaker on the firewall where the old regulator was removed. It has a manual trip button, which makes it handy as a master shutoff when working under the hood or dash. I'm very happy with the setup and, so far, the breaker has never tripped.

Steve