The Stovebolt Site Forums The Shop Area The Electrical Bay What kind of altenator do i need?

Hello fellow bolters,

I have a 1951 chevrolet 3100 (officially 1300 but its the same just the canadian name). Since me and my father got the truck the battery goes dead all the time. The problem is that the altenator is broken and doesn't charge the battery.
My question is: what altenator do i need? I currently have a Delco si-10. I found another one for sale on the web, but i don't know if this model is right for my engine.
Any help is appreciated!

with kind regards,

Thijs

(ps. the truck is completely stock and has a 216 inline 6)

Your Delco 10si will do just fine and preferred by many on this site. Make sure the pulley size matches the existing belt size. If it doesn’t, you can buy and change the pulley to the proper size. You’ll also need to either buy or fabricate a new bracket to mount it to the engine and a bit of rewiring is required.

If you are currently running a 10si then we must assume the brackets to mount it have already been fabricated. Just replace the alternator with the same part # that you now have and you are on your way. You have had your current alternator tested, right?

BTW: your truck is not “completely stock” since it didn’t come stock with an alternator. It had a generator from the factory. Therefore, it’s “mostly stock”, just being nit picky.

Another thing to consider when buying a replacement for your 10si is the "clocking" of your alternator. This article probably has way more information about alternators than you'll ever need, but it does a good job of explaining clocking.

I looked at a picture of your truck and there is a regulator on the firewall. Maybe it's not used anymore?

https://www.stovebolt.com/ubbthread...gs-from-the-netherlands.html#Post1431886

Some 10si alternators were converted to one wire alternators. The "DA" plug will be missing on these.

Perhaps you should post a picture of your alternator.

Regulator.
I believe I see 2 wires on the B (battery) terminal and none on the A (armature) and none on the F (field) terminal.
It is common to only use the B terminal when converting from generator to alternator.
It also means the truck has been converted from a 6 volt to 12 volt battery.
It would help if you would share any information you have about the wiring and any electrical updates.

That is a photo of the original regulator used with original generator. Show us a photo of the alt. with the connectors.

George

I know. That why it says "Regulator".

My bet is the wires from the original regulator don't go anywhere anymore. Internal regulator GM alternators came along about 1973 and is most likely what you have.
A picture of your alternator would be helpful.

Thank you all for your answers!

I will include some photos. About a month ago I replaced all the wires (hell of a job ) but all the wiring is correct. What we did do is to try and change the wires on the regulator like they originally were. (see picture) still no charging.

The altenator has two contact points on the top and one big on the back. If you look from the front of the car the two contact points are on 9 o'clock. The altenator itself sits on 5 o'clock of the engine (if you look from the front)

I opened it up to see if anything is damaged.nothing . Cleaned it up and put it back on. Still no sign of life.

We are going to bring it to someone who will rebuild it. But maybe somebody knows already what's wrong (like the position or wiring).

All help is much appreciated.

With kind regards,

Thijs

What plugs into the two wire connection on the alternator? and were does the wire go to? The alternator needs to see battery voltage before it turns on, if it's not wire correctly, it never turns on. A ONE wire alternator only needs the main heavy wire to work. There is a test port on the back of your alternator where you insert a probe to manually excite the regulator, but its been a really long time since I have had to do it, I couldn't tell you just where it is, any '65 or newer GM shop manual will be of some help.

That regulator shouldn't be wired in to anything.

That is an internal regulated alternator. It doesn't need or want an external regulator. If you wire it correctly it will more then likely work.
I can't explain how though in this post. If you get a wiring diagram off the internet or a manual, You can probably figure it out.


George

Dear Sir,
Please read carefully. If you have converted to 12V and have a 10si Delco alternator,

1. You DO NOT use a regulator.
2. You DO need a ballast resistor.
3. Wiring for alternator is as follows.
Wire from alternator terminal 1 to ignition switch ACC terminal. (or a separate ignition switch terminal than the battery connection)
Wire from alternator terminal 2 to big stud on back of alternator
Big wire from battery or starter to big stud.

Ignition wiring using 12V coil:
wire from ignition switch "ON" terminal to one side of ballast resistor.
Other side of ballast resistor goes to positive terminal on coil. Also a wire from foot start "side terminal" to coil positive terminal.

Assuming you still have original foot start and ON/Off ignition switch

Important: You say alternator has no sign of life. Hook it up as I describe, then put a volt meter/multimeter on alternator. Set to DC volts. Red lead to big stud, black lead to chassis ground, should read +/- 14V at medium high idle. Let us know what it does read.

thanks for all the reply's!

Bartamos thanks for the wiring. I heard from the friend of ours (who is really good in these things) there should be a little light connected. I also did some research again today. From what i found on the internet:

The cable from the big stud goes to the battery.
terminal 1 goes to a little light. and from this light to the ignition switch.
Terminal 2 goes back to the big stud.

is this correct? i made a little visual so you can see what i mean.

I really appreciate your instructions but I'm not that good with electrical wiring so i really need a visual otherwise I still won't understand

The drawing you have will work. It is a 3 wire alternator effectively hooked up as a 1 wire alternator with an "ALT" light on the dash. A 1 wire alternator has an internal connection duplicating the wire you have connected to terminal #2. The #2 wire connects output voltage of the alternator to the internal voltage regulator.

If you are not afraid of running one more wire, you could get a better operating system by removing the terminal #2 and replacing it with a wire that runs from #2 to common voltage distribution point back under the dash. That way the voltage regulator will be seeing the distribution voltage in the truck, which could easily be 1/2 volt (or more) less than the output from the big stud on the alternator. This is the way Delco designed the system to work. For more technical info about this click here.

But like I said, the system as you drew it will work.

Thanks Bill,

I guess the common voltage distribution point is the the place where 4 cables meet under the dash (don't really know which ones they were).

If so, i'm not really excited to put a wire back there. I recently replaced all the wires and put those cable in a little box which connect different cable together (don't know how its called). I will need to remove all the clocks on the dash to put that cable in. But I will think about it

For now, hook it up without the extra run wire and make sure it all works. As a test, you can hook up both #1 & #2 terminals to the main battery terminal, that will tell you if the internals of the alternator work. If it chargers, move the #1 wire to ignition source or Charge light in the dash cluster as you have it drawn.

Yes, that would be the place.

Like Joe says, leave it like it is for now. When you get to the point that you have nothing to do, consider moving it.

You don't "need" an indicator light. It is NOT necessary if the wire from no. 1 alternator goes to a DIFFERENT terminal on the ignition switch than where the battery hot wire is connected.

You can have a light if you want it wired as you have shown.

Don't get confused with a common point for now. I realize you are new to wiring so I am keeping it simple. Just wire it and start motor and test alternator output as I described. NO WIRES TO the old Voltage regulator.

Can you PLEASE confirm you have a 12V battery.
Can you post good pictures of your ignition switch and it's terminals or make a drawing.

Be sure to tell us what the alternator output voltage is,, don't just say "no sign of life".

If you need a new alternator THIS is the one you need.

Sorry for not giving a reaction was very busy the past days.

Unfortunately we still don't have a working altenator. Got a refurbished one from a friend of ours and tried to contact it as i had shown but we don't get anything. The output of the battery is still around 11 volts ,So it's discharging. (Yes we have converted to 12 volts)

Made a little drawing where the ignition goes to. Hope somebody can help because I really wanna give up

1. Is the "ignition light" just to see the key? or is it related to alternator?
2. Please clarify the last one to the right, can not understand what it is. Print your words more carefully. Be careful due to language differences.
3. Have you connected the alternator per our instructions?
4. You say battery shows 11V. How are you testing that? Where are your meter probes touching? Is motor running during test?
5. NEW TEST. Motor running...Meter positive probe on big stud on alternator. Meter negative probe on battery negative post. Report reading. We are trying to get the output of the alternator NOT the battery.
6. ALSO: test battery at rest with motor NOT running. Meter across battery posts. Don't touch the cable clamps, just touch the posts.

In your last drawing YOU DO NOT SHOW A CONNECTION TO THE ALTERNATOR!

Make sure your drawings show what you actually did NOT what you were supposed to do. Can you post pics of the alternator and it's wiring? So we can check you.

Keep in mind that if your battery is bad, you may not know it and that is really what your problem is. battery should read about 12.6 at rest and should show about 14V when motor running. With two alternators tried by you, it seems like it is the battery, cable connections, loss of ground or alternator wired wrong.

The alternator case must be grounded. This is accomplished by the alternator case being bolted to brackets on the motor. The battery negative cable is bolted to the motor to complete the path back to battery.. There can be no paint, corrosion, rubber or loose bolts at these location which would interupt the ground path

OK, I give up.

Hi Bartamos, I'm very sorry for not replying sooner to you.

Currently I am very busy and don't have any time at all to work on the truck. We have a nursery at home and these 2 weeks we need to plant cuttings (don't know if this is the right word for it, let's say they are very little plants). These plants are literally coming day in day out from all over the world and need to be planted almost instantly so they don't die. Hopefully you wil understand that I can't really reply to you with more information as I didn't have time to work on it.

Hopefully you still want to help me when I have more time

anyway i made some progress again today. Made a wiring diagram of the car itself. It's not complete but with the things you probably want to know (for anyone wondering how i made it, i use the site Lucidchart. Normally i use it to make proces charts for my study but you can use it to make wiring diagrams). Hopefully you can understand how it's wired and what the problem is.

To answer your questions Bartamos:

1. Is the "ignition light" just to see the key? or is it related to alternator?
The ignition light is to see if the ignition is on. When you turn the key to the right the light goes on, and when you turn it to the left it goes off (a little bit like the beep you get when you leave your ignition on in a modern car). It's so we don't accidentally leave the the ignition on. It's wired with one wire to a little light on a bracket. It has nothing to do with the altenator.

2. Please clarify the last one to the right, can not understand what it is. Print your words more carefully. Be careful due to language differences.
It's the point where the different cables connect. Bill called it the "common voltage distribution point", I call it a "cable connection point" myself. In the wiring diagram you can see that there are 2 different "connetion points" one for the interior lights, and one "big one" (i call it like that because the cables I put in it are a lot bigger) for the regulator, electricity gauge (meter on the clock wich shows if the battery is dead or charged) and the light switch.

3. Have you connected the alternator per our instructions?
I connected it as I had previously drawn and what I saw on youtube video's.

4. You say battery shows 11V. How are you testing that? Where are your meter probes touching? Is motor running during test?
We tested it by putting a annmeter on the + and - of the battery (and measuring with DC 20V on the annmeter). We test it when the engine is running.

5. NEW TEST. Motor running...Meter positive probe on big stud on alternator. Meter negative probe on battery negative post. Report reading. We are trying to get the output of the alternator NOT the battery
Haven't tested that yet, my dad had no time and I don't know if i'm doing it right when i'm doing it alone. We tried to test the altenator itself by putting the annmeter on the BAT point and the casing of the altenator itself (and on other ground points like the engine and the chassis)

6. ALSO: test battery at rest with motor NOT running. Meter across battery posts. Don't touch the cable clamps, just touch the posts.
Just did that, and it gives me the 11 volts. I know that the battery could be dead, but I expect atleast an increase in the voltage when the altenator works.

hopefully i answered your questions clearly. if not, please let me know
Hopefully you (or someone else) can find the problem.

Several important questions on diagram.

1. Does your word "annmeter" mean multimeter or voltmeter? If it means ammeter/amp meter, it is the wrong meter.
2. I see a component called "regulator" with only one wire going to it. What is that?
3. The alternator is not labeled. If the red and purple wire are on the same terminal, it looks correct.
4. I do not see a ballast resistor, so does coil say internally resisted?
5. Does "electricity gauge" mean ammeter gauge?
6. Clarify this comment you said..."for the regulator, electricity gauge (meter on the clock wich shows if the battery is dead or charged) and the light switch. THERE IS NO REGULATOR ANY MORE. NO REGULATOR. NONE. It is inside the alternator now. So what is the item you are calling "regulator" on the the diagram????
What is meter on clock? The ammeter? Are you calling it "meter on clock" and then calling it "electricity gauge" also???
7. DO NOT look at youtube videos for this.
8. Is the belt on the alternator and is the alternator pulley turning fast at medium high idle?

It seems you are saying the battery reads 11V with motor running or not. So that means battery is bad and you need to replace it, or it means you have the alternator wired wrong and it is not wired per your diagram like you think it is. It is hard to believe you have two bad alternators.

I WILL REPEAT WHAT I SAID IN PREVIOUS POST>
Make sure your drawings show what you actually did NOT what you were supposed to do. Can you post pics of the alternator and it's wiring? So we can check you.

Keep in mind that if your battery is bad, you may not know it and that is really what your problem is. battery should read about 12.6 at rest and should show about 14V when motor running. With two alternators tried by you, it seems like it is the battery, cable connections, loss of ground or alternator wired wrong.

The alternator case must be grounded. This is accomplished by the alternator case being bolted to brackets on the motor. The battery negative cable is bolted to the motor to complete the path back to battery.. There can be no paint, corrosion, rubber or loose bolts at these locations which would interrupt the ground path.

WARNING: I am not sure what an alternator will show on a volt meter if a battery has dead cells. Someone here can advise.

I will try to answer some questions as it's already 1 o'clock here in the Netherlands and I can't get to the truck now. Will try to answer the other questions tommorow when i can check.

1. Does your word "annmeter" mean multimeter or voltmeter? If it means ammeter/amp meter, it is the wrong meter.
Yeah i mean a multimeter just didn't translate it correctly . As you probably guessed i'm not from the states so English is not my native language, just trying my best!

2. I see a component called "regulator" with only one wire going to it. What is that
That's the regulator you mentioned i shouldn't use But I didn't know where I needed to put that cable so i just left it there. The cable itself goes back to the "big connection point"(see wiring diagram). Do i need to connect that cable somewhere else? or can I remove it completely (maybe i can use it to connect the #2 terminal on the altenator to the "big connection point" for a better working system as Bill mentioned.

3. The alternator is not labeled. If the red and purple wire are on the same terminal, it looks correct.
Sorry forgot to do that yes it's the altenator.

4. I do not see a ballast resistor, so does coil say internally resisted?
Honestly I don't know. For as far i know there is text on it that says that it's internally resisted. I also don't know if it's the original coil or a replacement as the previous owner painted it the same colour as the engine. Is there some way i can check if it's internally resisted or original (i know that there is a code on it). And can you please explain (if needed) where the ballast resistor goes and what it does?

5. Does "electricity gauge" mean ammeter gauge?
yes it does (it's on the left gauge cluster and then on the top right). Again sorry for my translation

6. Clarify this comment you said..."for the regulator, electricity gauge (meter on the clock wich shows if the battery is dead or charged) and the light switch. THERE IS NO REGULATOR ANY MORE. NO REGULATOR. NONE. It is inside the alternator now. So what is the item you are calling "regulator" on the the diagram????
as I already said, i didn't know where to put it or if the cable should be completely removed. I just left it there

What is meter on clock? The ammeter? Are you calling it "meter on clock" and then calling it "electricity gauge" also???
The ammeter gauge.

7. DO NOT look at youtube videos for this.
I'm 20 so I grew up with youtube. I know that the video's are not always right, but sometimes I can better understand something when I see it myself in a video.

8. Is the belt on the alternator and is the alternator pulley turning?
Yes belt is on the altenator and the altenator pulley turns.

It seems you are saying the battery reads 11V with motor running or not. So that means battery is bad and you need to replace it, or it means you have the alternator wired wrong and it is not wired per your diagram like you think it is. It is hard to believe you have two bad alternators.
All the battery's we place in the truck go dead at some point because it doesn't charge. We have an battery cutoff switch so the battery doesn't drain overnight. Sometimes my dad forgets to switch the battery off so it goes flat. When we tried the altenator (with engine running) we had the battery charged overnight. I guess the battery is at the moment flat, can try to charge it up tommorow or replace it with a good one and see what the voltage is. Need to check tomorrow.

I WILL REPEAT WHAT I SAID IN PREVIOUS POST>
Make sure your drawings show what you actually did NOT what you were supposed to do. Can you post pics of the alternator and it's wiring? So we can check you.
I don't really understand what you want me to do. Do you want me to show what I did (as that's the current wiring diagram) or how it was back when we changed some cables? please explain

Keep in mind that if your battery is bad, you may not know it and that is really what your problem is. battery should read about 12.6 at rest and should show about 14V when motor running. With two alternators tried by you, it seems like it is the battery, cable connections, loss of ground or alternator wired wrong.
will change the battery tomorrow.

The alternator case must be grounded. This is accomplished by the alternator case being bolted to brackets on the motor. The battery negative cable is bolted to the motor to complete the path back to battery.. There can be no paint, corrosion, rubber or loose bolts at these location which would interupt the ground path.
The altenator case is bolted to a bracked on the motor. I don't know if the battery negative cable is bolted to the motor (will check tomorrow).

sorry if it looks like you're talking to a dead mouse. I try to understand everything and do everything you say, but as you probably already guessed I don't have a lot of experience with wiring and cables. I'm just a 20 year old student business administration who tries to restore some parts of the truck by myself and wants to understand how everything works

OK I understand now. thank you. Don't worry about English translation if I need to clarify I will let you know. It can be very bad if I don't understand and then give advice.

Nothing to do except BE SURE wiring of alternator matches your diagram and instructions from us at stovebolt. NOT youtube. This wiring is very easy if you just focus on the alternator for now. I should not mention ballast resistor. You said coil has text saying "internally resisted" so no ballast is required. I will explain that later. The resistance is just to protect points during driving. (ignition system)

Yes... remove wire from regulator. For now you can wire alternator as you have shown. There is an ignition system and a charging system. Your motor starts (ignition) but no charging, so we will just talk charging for now. We will clean up ignition system later. Enhance the distribution.

A new good battery needs to be in place from now on. The battery will not run down overnight unless it is a bad battery. After charging it to 12.6 and just trying to get the alternator to work it will still have voltage. That voltage should be held overnight with no shut off switch necessary unless you have a battery drain. Meaning something is ON that should not be on. Just disconnect the negative battery cable at the battery post when done with testing that we ask for. So put new battery on, retest alternator output when motor running a fast idle. BE SURE to read about grounding battery to motor and grounding alternator case.
"The alternator case must be grounded. This is accomplished by the alternator case being bolted to brackets on the motor. The battery negative cable is bolted to the motor to complete the path back to battery.. There can be no paint, corrosion, rubber or loose bolts at these locations which would interrupt the ground path."

At your age and experience, you are doing very well. Once we get the alternator to charge a good battery, we will go over all other electrical systems with you so you can learn.
It would be nice to see many good pics of your alternator as installed. Also the wiring and where wires go. One thing we know for sure, something is wrong and we are trying to catch it from 7500 km away from you. You and your Dad will find it with our help.

okay so I think i found one of the problems.

When we put the the big cable (BAT point on altenator) to the starter, and turn the battery "cut off switch" ON, the big cable makes a short (it smokes and becomes very hot).
I think the problem is that the altenator that we got from our friend is a positive ground altenator.

4 reasons why i think this:
1. There is a sticker on the altenator that says that the altenator is for a Austin Healey 3000. I know for a fact that for 30 years almost all british sports cars were positive grounded instead of negative. We also have a MG B from the same period (1964) which is also positive grounded.
2. The altenator got rebuild. When it got rebuilded the BAT post on the altenator was switched (see drawing and pictures). Also I noticed that there was a red cable in the altenator case. For what i found on the internet these are part of some rebuild kits.
3. Delco Si-10 altenators can be rebuild from a negative grounded altenator to a positive grounded altenator. There are several kits you can buy online to do this.
4. Not a really good reason, but it is a reason . The Guy we got the altenator first said he didn't have the same type of altenator. When we looked between his spare parts (which is very organized and sorted on british parts and american parts) the altenator layed between the british parts. As i said, most of the british cars were positive grounded.

Now my question is: Is it possible that i get a short and the altenator doesn't work because the altenator is positive grounded?

It's not really a problem if the altenator is positive grounded. We made a deal with our friend that we got this altenator and the other one would be rebuild. So i could get the original altenator back!

Ps. Don't mind the connection to the starter. It's just temporarly and when the altenator works, i will put a better cable to it. It's just so that we can remove it easily (which saved us a burned vehicle because we could remove the cable quick when it became hot)

Also i checked if our Coil has a internal resistor, which it has. I checked the part number and i get an coil with an internal resistor. I mentioned that the Coil was painted with the engine. This was wrong, the orignal colour of the Coil is the same blue as the engine and, altough the stickers are gone, the residue left from the stickers are the same as the Bosch altenator.

I also checked the ground of the battery. I don't really know if it's rightly connected or not. There is no direct negative cable that goes from the battery to the engine (only a positive one that goes to the starter). When i check with a multimeter the engine is grounded to the chassis with a cable (see picture). The chassis is negative grounded to the battery through the "cut off switch". Is this right or not?

I put a good battery in it which reads 12,4 volts. So the battery is in good condition!

1. In your first pic you say "How it should be and how it was". Can you see the text in purple? It says Model 12si Delco. You said you have 10si. Which is kind of true. Maybe you already knew the old one was a 12si? If it matched your first pic.

2. In your second pic you say "our alternator". That seems to be a 10si. HOWEVER, the big battery terminal is in a different place than normal. You can see that the normal place just looks like a nut in your pic, but next to it says "BAT". I assume it is like that because it was converted to Positive ground but I do not know.

3. You can test the alternator, with all wires disconnected, to see which it is, positive or negative ground.
Use Multimeter set to ohms/resistance.

Positive probe on big bat stud, negative probe on case. Record reading.
Then reverse the probes. record reading.

A negative ground alternator will show high resistance when the positive probe is on the bat stud and show low when probes are reversed.

A positive ground alternator will show low resistance when the positive probe is on the bat stud and show high resistance when probes are reversed.

You said: The chassis is negative grounded to the battery through the "cut off switch". Is this right or not?
Please explain where the battery negative cable goes.
To the cut off switch? Thru the switch to the frame?

DO NOT use the word "chassis" when speaking about electrical. It is too vague. There is a frame, body sheet metal and the Motor. Normally the negative battery cable goes to the motor. Then there are straps from motor to the frame and from frame to body. It can vary as long as all three are connected. I do not recommend a cut off switch. Especially for a person with problems and a person looking to use a distribution point and eliminate so many connections/resistance points.

I recommend you order this alternator from AMAZON.NL. CLICK

Use the free trial, I do that all the time. CLICK

Just to answer your questions:

1. In your first pic you say "How it should be and how it was". Can you see the text in purple? It says Model 12si Delco. You said you have 10si. Whick is kind of true. Maybe you already knew the old one was a 12si? If it matched your first pic.
Our original altenator was a Delco Si-10. I used that picture to show were the stud is supposed to be. Couldn't find a better picture of a Si-10 so used this one. Same location (upperside left when the 2 terminals are pointed to above

2. In your second pic you say "our alternator". That seems to be a 10si. HOWEVER, the big battery terminal is in a different place than normal. You can see that the normal place just looks like a nut in your pic, but next to it says "BAT". I assume it is like that because it was converted to Positive ground but I do not know.
That was my also my guess. it is a si-10, but converted.

3. You can test the alternator, with all wires disconnected, to see which it is, positive or negative ground.
Use Multimeter set to ohms/resistance.

Tested the altenator and you can guess it... ITS a POSITIVE!!!
Used your technique (very helpful :D) and noticed that when I put the positive probe (red) on the BAT and the negative (black) on the casing it shows low resistance. Reverse the probes and its high resistance. Now i know that I have the wrong altenator and need to get the other one back!


You said: The chassis is negative grounded to the battery through the "cut off switch". Is this right or not?
Please explain where the battery negative cable goes.
To the cut off switch? Thru the switch to the frame?
So the negative cable goes from the battery, through a small hole in the floor and ends up on the cutoff switch which is connected to the dashboard. (see pictures) When we turn the switch to the left the ground is cut of from the battery so it doesn't go flat over night. I know it shouldn't go flat, but first i want to repair the altenator and then search where the battery loses its electricity.


DO NOT use the word "chassis" when speaking about electrical. It is too vague. There is a frame, body sheet metal and the Motor. Normally the negative battery cable goes to the motor. Then there are straps from motor to the frame and from frame to body. It can vary as long as all three are connected. I do not recommend a cut off switch. Especially for a person with problems and a person looking to use a distribution point and eliminate so many connections/resistance points.
I will look into that with my dad tomorrow. I do understand that you don't recommoend a cut off switch, but we use one in our MG B for years and never had any problem with it. I know that there is a loose strap inside the battery box which we removed for the cutoff switch, maybe that is connected to the engine!

I recommend you order an alternator from the states. CLICK [amazon.com]

Use the free trial, I do that all the time. CLICK [amazon.com]
I will look into that! tommorow morning i will call our friend about the altenator. The old altenator will be rebuild by someone who has a shop for that. So i will wait for the answer for that! Otherwise i will buy it from amazon, luckely the one you send ships to the Netherlands (very uncommon) so that won't be a problem!

I can't thank you enough for the amount of effort you put in it for me and that you are willing to share your knowledge! It helps a lot and without it i would never be able to repair it! I'm understanding more and more about how it all works

You are welcome. After the "new" alternator gets working, we will discuss other electrical systems as you wish. Does your truck have a foot start?

We called our friend today, and he will bring our old altenator to a rebuilder next week. So i think we will wait for that, as it would take 3 weeks for the altenator from amazon to arrive.

Just to satisfy my curiosity, are there Auto Parts stores in the Netherlands? The 10SI alternator is nothing special and every parts store in the USA has at least 2-3 in stock at all times. You’re doing great at keeping up with bartamos! The truck will be back on the road in no time.

Unfortunately there almost no Si-10 altenators for sale in the Netherlands. The cheapest ones for sale are more than 160 dollars . There aren't a lot of old American cars here on the road. Most of the old cars are from Britain, Germany or France. I guess they don't use those altenators. There is a online shop in the Netherlands which sells parts for old Ford and chevrolet trucks, but altenators there aren't delco si-10 and the cheapest one is 220 dollars. So a rebuild or getting it from the states is probably cheaper

Also to answer your question Bartamos, yes the truck has a foot start

You should begin sourcing a ballast resistor, an externally resisted coil and a starter switch with side terminal. The internally resisted coil method is not for our trucks. It is the wrong method. None of this is original to your year but the external R method is original to what was used when Chevy went to 12V.
Here are the parts, or an equivalent, you need:
Ballast Resistor

Starter switch

Coil

I will explain wiring these after you get them. You do not have to buy them, you can use what you have but there may be issues at some time. You can wait until the money is available or issues show up. (hard starting, points burning out, coil failure)

Bartamos can you please explain why I need those things? If you say so that I need them I will buy them. Also these parts are available to buy online in the Netherlands, so no expensive shipping costs . But I really want to know why I need it them, because we don't have any issues with starting the truck

If you have no problems, you can use what you have.
When GM converted to 12V in about 1955-1956, there was a problem. During starting, the starter takes a huge amount of the voltage/amperage until motor starts. When motor starts, starter no longer draws voltage, then voltage to the coil/points was too much. They like about 8V or they will burn out fairly quickly. So GM added what is called a "bypass" system. All other makers did the same for many years with some improvements. Owners of older trucks who convert to 12V must also add this bypass. This is done with the parts I listed. Those parts allow full available voltage to starter and points during cranking. When motor starts, voltage is reduced to points to about 8V thru a resistor. Ballast resistor. During cranking the ballast resistor is "bypassed" so full available voltage is given to points as mentioned. Then ballast resistor gets back in the system when motor starts.

The method used on your truck can be OK. It has less parts. Just an internally resisted coil. This coil provides the 8V to the points to protect them. But it is always 8V and during cranking of 12V starter motor,, the voltage to points drops and can create hard starting. This will show up on cold days when battery and oil flow is sluggish. Some motor parts may shrink in the wrong place. If there is also bad connections, corrosion or a weak battery.....no starting.
So you see why we say if you have no problems you are OK, but if you do, you will know why.