What was Ford’s stock alternator’s output on the 66 and 67’s?

[Gas Pig]

Do anybody know what was the stock alternator’s amp output (38A, 42A, or 55A) Ford used on the ‘66 170 and/or 289?

Thanks Jeff

 

[Broncobowsher]

Everything I have ever read says they were all 60A (55A) alternators. The same case was used on the 40A (38/42A) but just different guts.

It's hard to find one that has not been rebuilt or replaced by now. 60A is the general replacement.

 

[B RON CO]

Hi, it is my understanding the entry level Broncos, Falcons, etc used the 38 amp alternator.
As mentioned, the 60 amp is the one to get, along with an electronic voltage regulator.
Good luck

 

[jckkys]

I still have my original '68 that always did everything I asked of it is 40A. I use a 100A now, but can't see any advantage to it over the 40A.

 

[Gas Pig]

Thanks guys for your input!!! I primarily wanted to know so I could detail out my ‘66 Bronco so I get the right Autolite alternator stamping for my rebuilt original Autolite alternator. I have a couple ‘66 and ‘67 builds coming up and I love doing as much fine detail as I can... little things like that are not a show stopper but can look great if done properly.

Thanks again for all of your guys help!
Jeff

 

[SHX669]

I'd say that 38A is correct for stock and 55A was the option - in 1971 it was a $31.40 option.

 

[EricLar80]

I still have my original '68 that always did everything I asked of it is 40A. I use a 100A now, but can't see any advantage to it over the 40A.

Unless you are running a bunch of accessories, you wouldn't see an advantage. What's the benefit of having a garden hose to drink from when you are unable to drink more than what is provided by a straw?

 

[jckkys]

To clarify, with headlights, and heater blower/wipers on high the battery was still being charged. The idiotic idea that bigger is always better, failed in this case. The 100A alternator required a 2 groove pulley to stop the start up squeal.

 

[EricLar80]

The true upgrade in this case would have been a serpentine system. Can't beat it unless you want it to look original.

 

[Broncobowsher]

My f250 I specifically was looking for the lower output 3G alternator. Single V-belt is happy and enough amps to run the added EFI even at idle. Biggest isn't always best.

 

[EricLar80]

My f250 I specifically was looking for the lower output 3G alternator. Single V-belt is happy and enough amps to run the added EFI even at idle. Biggest isn't always best.

But that is ignoring all of the advantages of the serpentine, and only looking at whether it can perform it's most basic function.

 

[jckkys]

If I loose one of my V-belts I can drive home. If I loose the serpentine belt on either of my newer cars my day is done. Serpentine belts have few if any advantages. The harmonic dampers that include the pulley often come apart. The V-belt dampers have never failed for me on any vehicle, even the 50yr. old Bronco dampers. If there isn't a clear advantage in any late system I won't change over to it. As bigger isn't always better neither is newer.

 

[EricLar80]

Why is your day done? Every parts house carries them in stock, and I bring a spare when on the trail. Takes 30 seconds to change it. But they usually last 60k miles, so not sure why it would fail in the first place. We aren’t protecting against severe lack of maintenance as a reason, are we?

 

[DirtDonk]

I've got spare serpentine belts in all of my vehicles. Usually I get the new one fairly early one, or at least before any kind of trip. Stays in the trunk or box.
Before it's really time to change the old one out, I replace it with the new one anyway. That way I still have a relatively new one on the vehicle and a good used spare in the trunk.

Never lost one, but people I know have.

I had dual V-belts on my '71 as well, to get rid of the squeal on the large case 70a 1G alternator. Busted a single belt on a Death Valley trip, but the second one kept me going once I got the debris of the old belt out of the harm's way.

I don't have much issue with either type, but would change every V-belt I own to a serpentine in a heartbeat if I could.

Paul

 

[BwoncoHowie]

I still have my original '68 that always did everything I asked of it is 40A. I use a 100A now, but can't see any advantage to it over the 40A.

I had the 55A on my '73 when I bought it. The headlights would dim @ idle and the amp gauge would go to battery power.

I installed the large housing 100A out of an 88 taurus. A junkyard unit that I put bearings and brushes in. No wire mods necessary because it is externally regulated like the factory stock unit. Connect orange wire to field prong, and the Black/Wht. wire to the stator prong. Mine had the old mechanical regulator, so I changed that too, to a Motorcraft electronic voltage regulator.

There is a lot more copper spinning around in these large housing alternators so they don't have to work as hard. Result, headlights don't dim @ idle any more and it puts out 70A+ now during idle depending on load requirements.

Oh yeah the belt used to squeak with the stock alternator as did the Lg one. fixed that problem by taking off the rigid fan and installing a 7-blade flex fan. It took care of the squeal right away. But the large case alts. are sensitive about pulley size. I had to experiment with that and found that the 1-7/8" diameter worked the best for my needs.

 

[nvrstuk]

You mentioned stock so this pic shows how fast your alternator requirements can grow with modifications!! I was adding up all the stuff on mine (not fuse ratings) and thought the pic might be easier. Just an example below.

Don't forget to add in things like :

Electric seat heaters, air conditioning (20+ amps), winch (if you wheel), etc

Sorry the pic rotated...

 

[okie4570]

From the back of the 66 owner's manual

 

[nvrstuk]

I remember lights dimming, heater motor slowing down, wipers slowing to a crawl (after I upgraded to electric back in '77)...why would ya want all those "positives" unless you're trying to stay bone stock??

 

[DirtDonk]

My reason for getting a larger one was that I kept wearing out bearings on the smaller ones. They never failed to charge, but often made lots of rattling noises as the bearings wore out.
In hindsight it was probably just cheap parts. After the original one went out (I think it was a 55, but will have to look at my Marti to see if that's correct) I would put in just the regular 29.95 rebuilt ones from Kragen. They had always lived long on our other cars, but only lasted 1-2 years on my Bronco. Maybe cheap, or used parts, but I know I was never one to over-tighten the belts.

Went with the big case 1G 70a model too, and never had to replace another alternator. Ended up putting it on a friend's Bronco which I think ended up on member MtFit's Red Buggy. Probably still working for all I know!

It was a great bonus that the idle power was much greater and no more low speed dimming.
Have the 100a version on the pickup and it's got the larger pulley so no squealing either. Maybe the shorter run of charge wire helps too? Goes straight to the battery rather than around the truck for the ammeter.

Either way you go, whether you really need more power or not, it's not a downgrade to go bigger when you're no longer stock anyway.

Paul

 

[BwoncoHowie]

My reason for getting a larger one was that I kept wearing out bearings on the smaller ones. They never failed to charge, but often made lots of rattling noises as the bearings wore out.
In hindsight it was probably just cheap parts. After the original one went out (I think it was a 55, but will have to look at my Marti to see if that's correct) I would put in just the regular 29.95 rebuilt ones from Kragen. They had always lived long on our other cars, but only lasted 1-2 years on my Bronco. Maybe cheap, or used parts, but I know I was never one to over-tighten the belts.

Went with the big case 1G 70a model too, and never had to replace another alternator. Ended up putting it on a friend's Bronco which I think ended up on member MtFit's Red Buggy. Probably still working for all I know!

It was a great bonus that the idle power was much greater and no more low speed dimming.
Have the 100a version on the pickup and it's got the larger pulley so no squealing either. Maybe the shorter run of charge wire helps too? Goes straight to the battery rather than around the truck for the ammeter.

Either way you go, whether you really need more power or not, it's not a downgrade to go bigger when you're no longer stock anyway.

Paul

Yup I agree Paul.
I liked the Lg 100A on the 73 bronco explorer so much that i built another for the 77 F-150. It feeds the odyssey AGM battery very well. I use the truck to Jump-start a lot of vehicles regularly and the 100A brings up completely dead batteries very quickly with a 6 AWG charge wire.