Electric Choke

[CountryBumkin]

On Garagemahl, site there is some info at Fuel Systems>Chokes that has a link back to FTE where this info below is from.

I am putting together a write up on the 3G Alternator conversion, and one area that I'm not quite sure about is when one converts to the 3G (all of the conversion posts I've read/researched) say if you have th eold style 7.5V choke style, you should swap to a 12V choke cap. But I wondering if the stator terminal on the 3G is the same as the stator termainal on the 1G.

Does a 12V choke conversion need to be done or can one tie into the "S" term of 3G for the choke connection?
____________________________________________________________________________________

 Electric assist.
 There are many misconceptions about this power source, so let me clear them up now. In the factory configuration, the wire that powers the choke comes from the neutral point of the stator of the alternator. The stator is the part of the alternator that sits still (stationary) as opposed to the rotor which is what actually moves. The voltage seen at the stator is not a DC signal. It's not the same thing as pulling power from the battery, or power at the ignition key. The voltage here changes as the rotor moves inside the alternator and is therefore an AC signal.

Because of the configuration of the stator, the signal is referred to as a three-phase signal. That is your fun fact for the day. The reason all this makes a difference is because if you use your voltmeter to look at the choke voltage, you will only see around 7 volts DC. This is because the signal on the stator is actually all over the place, and the mean seen by the meter is around 7 volts. Why am I telling you this? Because many times, when diagnosing a problem, people will look at the voltage here and see that it's not 12 volts, and think there is a problem. You are not supposed to see 12 volts. The power from the stator is still more than enough to do the simple job of heating the choke.  

Edit: figured out to quote. Use the "<" and ">" rather than "[" and "]" like the other forum.

[Gary Lewis]

That is a good question for Jim, as I think he's talked about that before - although I don't know where.

The schematic for the various alternators, shown here, look to be the same as for the stator connection.  I'd bet they are, but don't know for sure.

[85lebaront2]

Yes, the 3G does have a stator connection, it is the small plug that only goes into the back near the main plug and has a wire going into the regulator plug.

[ArdWrknTrk]

The stator terminal on a 130A 3G is by itself instead of part of a multi prong plug like the 2G.

Most people doing this swap use the pigtail for an A/C clutch. (single gray locking connector)
You can splice both wires to this connector or use a 'piggyback' spade connector,  covered in heatshrink tubing.
This kind of terminal/connector seems to be common in the HVAC trade.

I've been thinking of a carburetor swap and have to consider a little rewiring of my alternator anyway.
If I have a phone with a camera that can focus by then I will take pictures of what I remove.

[Gary Lewis]

So, we now know that the 3G has the stator connection. Now we need to answer your question of "Does a 12V choke conversion need to be done or can one tie into the "S" term of 3G for the choke connection?"  And that depends on the rated voltage of the choke. Obviously the Ford style 7v chokes will work, but even the later 12v chokes will operate.  I successfully ran an Edelbrock's 12v choke coil off the stator terminal on a 1G. And assuming that the 3G's stator has essentially the same voltage I think it would work.

However, I should quickly say that I later added a relay to the mix and put 12v directly to the choke, pulling the relay in by the stator current. I made that change because I didn't think the choke was coming fully off when powered by the stator. As it turned out it was, it just took longer to do so.

[CountryBumkin]

Thanks - so the 3G stator output and the 1G stator output are the same.

Then anyone converting a 1G to a 3G does not need to update their old style 7V choke cap to a 12V.

I need to revise the last section in my "3G Conversion" thread.

[Gary Lewis]

Ok. Tell me what to remove and I can. Or, change as they'll need to know which terminal is the stator terminal and what to do with it.

[CountryBumkin]

I don't have the 3G Conversion write up on this computer - but from memory, it was the very last paragraph. There is a picture of the Holley Choke Cap and Oil Pressure Switch. You could just insert in that section some additional wording like:

"The 3G Alternator has a "Blk/Wht" wire going from the center of the plug running to a terminal on the alternator body. This wire is the stator wire. You can tap into this wire to power your (old style 7.5V) choke  or you can convert the 7.5 choke to 12V following the instructions here."

[Gary Lewis]

Mike - Please see what you think: http://www.garysgaragemahal.com/3g-conversion.html  I only changed the in-line version, not the tabbed one, as that was easier.  But, I can do the tabbed one if you want.

Anyway, here are the changes I think I made and things that maybe should be considered:

1. Under "Why Not" #3 says "I have a 7.5V electric Choke and I don’t want to swap it to a 12V Choke and go through the trouble of re-wiring this."  Can we take this out?
   
   
2. Right above the pics of the 7" and 8.25" there is this phrase "* Trucks that currently have V-Belts use the 8.125” mounts, and trucks that have serpentine belts use the 7” mount spacing. (* Need to verify this info)."  In red to make sure it isn't missed.
   
   
3. I rearranged the text and pics of "clearanceing" the serpentine mounting bracket and the ones about flattening the arm.  See what you think.
   
   
4. In the discussion about the voltmeter I added a link to Rocketman's conversions.  See what you think.
   
   
5. And I did change the wording on the electric choke.  Again, see what you think.

Gary

On Tue, Aug 15, 2017 at 9:54 AM, CountryBumkin [via Bullnose Enthusiasts] <[hidden email]> wrote:

I don't have the 3G Conversion write up on this computer - but from memory, it was the very last paragraph. There is a picture of the Holley Choke Cap and Oil Pressure Switch. You could just insert in that section some additional wording like:

"The 3G Alternator has a "Blk/Wht" wire going from the center of the plug running to a terminal on the alternator body. This wire is the stator wire. You can tap into this wire to power your (old style 7.5V) choke  or you can convert the 7.5 choke to 12V following the instructions here."

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[CountryBumkin]

Gary,
I agree with the changes (the part about removing #3 in the "Why Not" section. And the additional language added for the Choke connection and other changes (the link, flattening and rearrangement).
It all looks great.
Thanks

On the question of what mounting ear spacing is needed - I think we are going to need some feedback from members to know for sure. In all the 3G conversions I read about it was never clear to me which "donor" models have the 7" and the 8-1/4" spacing. If owners of truck with v-belts and serpentine belts report back what spacing their alternators have we would know for sure (or maybe the parts book has something on this).

Maybe the best thing to do, is just make people aware to check their truck mounting brackets (their current 1G or 2G spacing) so they know what to look for when they source the 3G.

The best I could find was the part about V-belts using 8-1/4 spacing and serpentine belts having 7" spacing. But I'm not sure this is always true. My 82 F250 (came with 351W with V-belts) has an alternator that has 7" spacing so that would contradict the statement in red. But... when I swapped in the 460, I also converted to a serpentine belt setup off a 1990 F-series with 7.5L BUT I don't recall ever replacing the alternator (which means my truck came with a 7" spacing alternator - or my memory is shot. It could be either).

[Ford F834]

Wow! Thanks Mike and Gary for putting this together. Electrical is definitely my weak suit and I will need this when I go about wiring in my 1994 serpentine 7.3 into my 1986 truck.

The only constructive criticism I have is it looks like the screen shot of the voltmeter gauge conversion unit may be out of place within the text?

And I do have a question: in the text it says Ford started using 2G in 1986, but my 1986 F350 was set up with an external regulator, so 1G correct? Was this most likely stock or did someone back convert it? It's the 6.9 IDI with dual batteries if it makes a difference. Thanks again.

[Gary Lewis]

Mike - I've made the changes we agreed, and made the one Jonathan found as well.  However, I'm not sure we even need the voltmeter screen shot since I put the link to Rocketman's site in there.

Jonathan - Thanks for catching that.  As for the alternator, I can't tell definitively from the catalog when the 2G's were introduced.  Here's an example of what I see.  The D9PZ or F0PZ regulators are external, and the E73Z is internal.  In other words, 1G and 2G.  But, there's no way to tell when they were used.  

[CountryBumkin]

I agree that the photo of the Ammeter to Voltmeter can be deleted.
On the transition from the 1G to the 2G, from what I read it started with the F-150. However with Ford, one can never be too sure. It seems like Ford like to make changes in mid-year too.

Keep in mind that I put together the 3G conversion doc, but I am no expert in this area. I haven't even done the conversion on my own truck (but I am doing the Ammeter to Voltmeter conversion).

So if there are any mistakes, or missing tips, please let us know.

[CountryBumkin]

Oops - there's a typo in my 3G write up.
This part Trucks that currently have V-Belts use the 8.125” mounts, and trucks that have serpentine belts use the 7” mount spacing. (* Need to verify this info)

The size mounting spacing is 8.25" not 8.125". The picture shows the correct dimensions.

Not sure if I should have e-mailed this to you, Gary - or if posting it here is good enough. But your the only one that can fix this.

[Gary Lewis]

What typo?  

[CountryBumkin]

8.125 should be 8.25
Oh wait, your being factitious facetious

[Gary Lewis]

Me?  Facetious?  I can't even spell it, much less do it.  

[CountryBumkin]

yea, that

[JimsRebel]

First, great 3G swap article.

My 1986 F150 4.9 lariat came stock with a G2 ALT. My engine has a single V-belt on the ALT.

1G, 2G and 3G ALT all have the same stator output.

I measured my spare 3G 130 amp ALT and I got 8.125 inches, centerline to centerline on the mount bolts.

There is some bad info in the first post with the long quote, the stator output wire never connects to the “neutral point”. Meaning the center of the Y (wye).
On a 1G and 2G ALT , the center of the wye is crimped together and is not brought out of the stator. This crimp point is the floating neutral point. Only 3 wire exit the stator. These are the 3 wires that feed the rectifier. The “stator wire” is attached to one of these 3 feed wires.

Also 1G and 2G ALT only have 6 diodes. The rectifier schematics from RJM are not correct.

On a 3G ALT, the center point of the Y is not crimped together. But instead both ends of the three coils pairs exit the stator. Thus 6 wires out of the stator and a much more complicated 8 diode rectifier.





Jim

[Gary Lewis]

Jim - Let me see if I understand.  The 1, 2, and 3G alternators have the same stator voltage output.  But, the stator output isn't 3-phase, it is probably single-phase.  Do I understand correctly?

But, other than the 8.25" measurement actually needing to be 8.125", none of that changes the write-up?