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raygreenwood
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Joined: November 24, 2008
Posts: 23136
Location: Oklahoma City
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 Posted: Sat Aug 02, 2025 4:55 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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So, when you apply vacuum to the outer chamber (advance) ....it pulls on the rod inside against a spring. So, yes. When you screw the screw in clockwise, it limits how far the diaphragm can pull the rod.
It's just a stop so it does not change tension on the spring so it advances at the same level of vacuum.
Ray |
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Jeremiah Berger
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Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 6:58 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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| raygreenwood wrote: |
Glad you tore this apart. I have several I have done this to over the years. I am not sure if I ever posted those pictures.
I actually uncrimped mine all the way around...trashed a trashed one figuring out how to do it without dangling it so I could crimp it back together.
For a long time I worried about what exact material to make the diaphragm from. But after looking it over and realizing that as long as it was che.ically decent, thin enough to fit and could handle about 250° F....it really does not matter. It's all about vacuum area and spring tension.
But today ai spent about 20 minutes taking a few pictures of about five different part numbers all of which can work with some small mods. I point out the details other than just internal spring tension that make them different to each other and post tomorrow or Sunday. Ray |
Yeah I would definitely still be interested to have that information for the future if needed . Thanks.
So if I turn the screw on the vacuum unit clockwise does that lessen the total advance? Do you know how many turns achieve how much? |
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raygreenwood
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Joined: November 24, 2008
Posts: 23136
Location: Oklahoma City
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| Posted: Fri Aug 01, 2025 6:05 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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Glad you tore this apart. I have several I have done this to over the years. I am not sure if I ever posted those pictures.
I actually uncrimped mine all the way around...trashed a trashed one figuring out how to do it without dangling it so I could crimp it back together.
For a long time I worried about what exact material to make the diaphragm from. But after looking it over and realizing that as long as it was che.ically decent, thin enough to fit and could handle about 250° F....it really does not matter. It's all about vacuum area and spring tension.
But today ai spent about 20 minutes taking a few pictures of about five different part numbers all of which can work with some small mods. I point out the details other than just internal spring tension that make them different to each other and post tomorrow or Sunday. Ray |
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Jeremiah Berger
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Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 5:53 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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I decided to give fixing this diaphragm a try and I am happy with the results. Works like it should and should probably last a little while...
I opened it up by grinding away the lip and leaving four tabs to be able to clamp it back shut.
I found a small pin hole/burn hole right at the vacuum inlet. I used flex tape to add a layer to the entire diaphragm and than used a razor to cut out the inner circle and stretched it the rest of the way over the center piece.
The results are an entire lamination of the original diaphragm and it stretches and works like original.
Holds up to 15hg with no leak down whatsoever...
I put some sealant on the sealing surfaces of the diaphragm material.closed it up with the four tabs and added a layer of JB weld after vacuum tested. I should be able to clean up the JB and polish it up to barely noticeable.
I think the 123 is still something I will consider but hopefully this works for a while until I can afford one.
I also loosened up the adjustment screw and got it moving. Next step is to understand how to adjust it exactly. If I turn the screw clockwise i lessen the advance is what it seams to me. Is that correct? |
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heimlich 
VWNOS.com
Joined: November 20, 2016
Posts: 7502
Location: Houston, Texas
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| Posted: Fri Aug 01, 2025 1:19 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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Ask Ray about it. I seem to recall mentioning something like this to him before and the reply wasn't as expected.
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Jeremiah Berger
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Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 1:15 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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Hmmm? Interesting. The only question I have is it says in the description that it has an angled distributor cap.
I'll do some more research later .
Thanks |
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heimlich
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Location: Houston, Texas
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Jeremiah Berger
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Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 11:18 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| heimlich wrote: |
Does 123 have a programmable unit that has the trigger points? You want the programmable one.
Share the links and I can look at it for you. |
As far as I can tell they do not. When I first started looking I thought that was gonna be an option but it seems that the only model with hookups for injectors is the Switched version.
https://lnengineering.com/products/aircooled-porsche-parts-and-upgrades/123-ignition.html?mode=list |
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heimlich
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Joined: November 20, 2016
Posts: 7502
Location: Houston, Texas
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| Posted: Fri Aug 01, 2025 11:08 am Post subject: Re: Jeremiah's 73 412 restoration project |
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Does 123 have a programmable unit that has the trigger points? You want the programmable one.
Share the links and I can look at it for you.
_________________
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Not all parts are made the same. NOS OE/OEM parts made mainly in West Germany, Early Germany, and Early Brazil are where VW produced the best quality parts and best fitting products.
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Jeremiah Berger
Samba Member
Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 11:05 am Post subject: Re: Jeremiah's 73 412 restoration project |
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My next question is am I going to be happy with one of the 16 preset curves that come pre programmed on the 123? You can look at the chart on the type 4 store if you look at the product description...
Would be awesome if I could just get a tune or tune+ version Wich let's you set the curve to exactly what you want but the one that is compatible with the djet is the Switched version.
I am only starting to understand advance curves and I'm not sure exactly what I am gonna want with this cam. I'm also not exactly sure how to make sense of the chart. I read somewhere that the advance starts at the same point on all them which is 12* but I'm not sure? Or they start at 2* but plus the 10* static that you start it at.Its kinda confusing seaming. Wich obviously you can get more by adjusting static but that effects total.So I'm not sure if the total advance on the chart is your actual total advance or you add that to the static you start at. Obviously this can all be checked with a light but I wanna know that it will work before I buy it ..
On that note how on earth is type 4 store charging $225 more for the exact same part as heritage parts?$625 vs. $403 Am I missing something here?
Ray, I know you have considered getting a 123. Have you looked at the preset curves and how they might play with upgraded cam djet etc. Do you have an opinion on wether this would be a good distributor for my setup and cam? |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 7502
Location: Houston, Texas
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| Posted: Fri Aug 01, 2025 10:42 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| Jeremiah Berger wrote: |
I actually emailed you too . So yes I'm actually trying to achieve a whole different curve at this point because I rebuilt it with a new cam and it now wants 12-14@ idle so I was hoping to get my adjustable unit replaced or find a unit to add an adjustment screw so I can limit the advance. That's my ultimate goal.Im looking more at the 123. Thanks for looking. |
That might be possible. I think you could take one of the very early SVA vacuum canisters and attach it. That would give you a whole bunch of advance at idle. You would need to limit it.
The problem is with all that advance at the beginning you will get it at the top end too. Your mechanical will be added to it. In the graph I showed you get 27 degrees. Add 12 to that and you are at 39 without any timing adjustment.
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Jeremiah Berger
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Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 9:57 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| heimlich wrote: |
| Jeremiah Berger wrote: |
| heimlich wrote: |
| Jeremiah Berger wrote: |
distributor part # 022905205 |
What's the letter(s) at the end?
You mentioned you have the trigger points. Do you have them in the side of the distributor? |
Sorry I didn't see that the first time...it's P
022 905 205 P
Or Bosch # 0 231 172 019
The armature on the vacuum has 917 stamped on it. Yes it is a trigger points in the distributor, for a d-jetronic . |
I would not purchase a rebuilt unit or pay to have your unit rebuilt unless you want to keep it original. 123 is the way to go.
If you need the small fiber washer that goes on the inside let me know. I can stick one in the mail for you.
If you put that vacuum advance on your car you will need to pin it so that it doesn't advance too much. Your stock distributor calls for 4 degrees (8 at the crank max). The one you pictured in a stock setting can give 6 degrees (12 at the crank). So you will want to make sure under full load and rpm you are not going over the limit and doing any pinging/etc.
I was trying to find a used canister I could send you but nothing matches the one you need. If you want a used one you can pin it to stop it from over advancing.
Keep in mind when it comes to some of these parts you are competing with Porsche people which will pay 3 times the price of VW. I'm sure you've already witnessed this.
Here is the advance curve of your distributor:
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I actually emailed you too . So yes I'm actually trying to achieve a whole different curve at this point because I rebuilt it with a new cam and it now wants 12-14@ idle so I was hoping to get my adjustable unit replaced or find a unit to add an adjustment screw so I can limit the advance. That's my ultimate goal.Im looking more at the 123. Thanks for looking. |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 7502
Location: Houston, Texas
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| Posted: Fri Aug 01, 2025 9:28 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| Jeremiah Berger wrote: |
| heimlich wrote: |
| Jeremiah Berger wrote: |
distributor part # 022905205 |
What's the letter(s) at the end?
You mentioned you have the trigger points. Do you have them in the side of the distributor? |
Sorry I didn't see that the first time...it's P
022 905 205 P
Or Bosch # 0 231 172 019
The armature on the vacuum has 917 stamped on it. Yes it is a trigger points in the distributor, for a d-jetronic . |
I would not purchase a rebuilt unit or pay to have your unit rebuilt unless you want to keep it original. 123 is the way to go.
If you need the small fiber washer that goes on the inside let me know. I can stick one in the mail for you.
If you put that vacuum advance on your car you will need to pin it so that it doesn't advance too much. Your stock distributor calls for 4 degrees (8 at the crank max). The one you pictured in a stock setting can give 6 degrees (12 at the crank). So you will want to make sure under full load and rpm you are not going over the limit and doing any pinging/etc.
I was trying to find a used canister I could send you but nothing matches the one you need. If you want a used one you can pin it to stop it from over advancing.
Keep in mind when it comes to some of these parts you are competing with Porsche people which will pay 3 times the price of VW. I'm sure you've already witnessed this.
Here is the advance curve of your distributor:
_________________
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Classic Brands. Classic Quality.
Not all parts are made the same. NOS OE/OEM parts made mainly in West Germany, Early Germany, and Early Brazil are where VW produced the best quality parts and best fitting products.
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Jeremiah Berger
Samba Member
Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 9:11 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| heimlich wrote: |
| Jeremiah Berger wrote: |
distributor part # 022905205 |
What's the letter(s) at the end?
You mentioned you have the trigger points. Do you have them in the side of the distributor? |
Sorry I didn't see that the first time...it's P
022 905 205 P
Or Bosch # 0 231 172 019
The armature on the vacuum has 917 stamped on it. Yes it is a trigger points in the distributor, for a d-jetronic . |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 7502
Location: Houston, Texas
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| Posted: Fri Aug 01, 2025 6:44 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| Jeremiah Berger wrote: |
distributor part # 022905205 |
What's the letter(s) at the end?
You mentioned you have the trigger points. Do you have them in the side of the distributor?
_________________
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Classic Brands. Classic Quality.
Not all parts are made the same. NOS OE/OEM parts made mainly in West Germany, Early Germany, and Early Brazil are where VW produced the best quality parts and best fitting products.
5% Off your order with coupon code: 5%OFF
Restored Distributors Available (<--Click here) |
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Jeremiah Berger
Samba Member
Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 4:41 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| heimlich wrote: |
Those bulbous units come from China. I've never liked them.
I have original Bosch ones made in Mexico so maybe that is why.
You have to be careful buying vacuum canisters like that. They are very generic. Although vacuum canisters look the same they have different properties.
Which distributor do you have? |
Yeah I kinda figured that, you have to be careful buying just about any aftermarket part these days because that's pretty much always the case.
Only reason I consider it is wwith something like this it seams like your options are not many.Just seams silly to put a used one in and hope it's not on its last leg. And OEM ones I've seen are so expensive if rather put that money to a 1-2-3. Considering the 1-2-3 because not only can I fix this issue, I solve my advance issue potentially It also cures any issues I may have or get with my trigger points. And upgrade from points to electronic ignition.
But considering I'm not made of money like I wish I was ...I need to try to find a reasonable priced vacuum unit first if I can and make it adjustable.
distributor part # 022905205 |
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Jeremiah Berger
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Posts: 166
Location: MAINE
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| Posted: Fri Aug 01, 2025 4:08 am Post subject: Re: Jeremiah's 73 412 restoration project |
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| Pepperbilly wrote: |
Guess I got lucky with mine because it still works after all these years. It is the original without any adjustment…no screw. I always wondered why some came with the adjustable screws and others like mine did not? We have same year automatic 412s with the same engines.
Bill |
I think I read somewhere that the distributors where fit by the dealership? Maybe Ray can chime in on that. I believe it was something he wrote. Or if not maybe they where different for places with emissions regulations? |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 7502
Location: Houston, Texas
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| Posted: Thu Jul 31, 2025 5:40 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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Those bulbous units come from China. I've never liked them.
I have original Bosch ones made in Mexico so maybe that is why.
You have to be careful buying vacuum canisters like that. They are very generic. Although vacuum canisters look the same they have different properties.
Which distributor do you have?
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Not all parts are made the same. NOS OE/OEM parts made mainly in West Germany, Early Germany, and Early Brazil are where VW produced the best quality parts and best fitting products.
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Pepperbilly
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Joined: April 08, 2017
Posts: 1082
Location: Seattle, Wa
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| Posted: Thu Jul 31, 2025 5:29 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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Guess I got lucky with mine because it still works after all these years. It is the original without any adjustment…no screw. I always wondered why some came with the adjustable screws and others like mine did not? We have same year automatic 412s with the same engines.
Bill |
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Jeremiah Berger
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Joined: September 16, 2018
Posts: 166
Location: MAINE
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| Posted: Thu Jul 31, 2025 2:16 pm Post subject: Re: Jeremiah's 73 412 restoration project |
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Ok I found this one available new that says it was for type 4 . I'm not sure if it would be compatible?...it a single vacuum.
https://mrfiat.com/products/volkswagen-type-4-vacu...98-2079-01
There's also a similar one on cip1 and they are both reasonably priced.
There's also some used units on the samba.
If I can find a reasonable priced vacuum unit then I would attempt to add the adjustment screw.
But if I have to spend hundreds getting this one working I would definitely consider just getting a 1-2-3. |
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