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Scrapefest
Samba Member
Joined: May 23, 2005
Posts: 34
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 Posted: Fri Nov 26, 2021 5:10 am Post subject: Type 4 , timing is slow to retard. |
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I have a W code 1700 type 4 engine in a baywindow . I have recently refitted PDSIT carbs and a vac advance distributor with dual vac ports. I cannot see where to attach the retard side of the vacuum canister to so at the moment it is just connected on the advance side. And is timed at 7° at idle max 30° ( vac hose disconnected) .
The problem I am having is with the vac advance connected after I rev the engine and let it return to idle, the timing hangs at about 16-20° . If I rev it without the vac advance the timing drops back to 7° quickly.
I have closed the throttle plates to make sure there is no vac advance at idle.
Does anyone have an idea of how to stop the vacuum from causing the timing to hang. |
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Alstrup
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Joined: July 12, 2007
Posts: 7214
Location: Videbaek Denmark
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| Posted: Fri Nov 26, 2021 5:34 am Post subject: Re: Type 4 , timing is slow to retard. |
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Hello.
The W engine did not come with dual vacum distributors, but since you are detuning it with bus carbs you simply have to take vacum from the left mainfold, and you should be in business
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Scrapefest
Samba Member
Joined: May 23, 2005
Posts: 34
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| Posted: Fri Nov 26, 2021 5:50 am Post subject: Re: Type 4 , timing is slow to retard. |
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| Alstrup wrote: |
Hello.
The W engine did not come with dual vacum distributors, but since you are detuning it with bus carbs you simply have to take vacum from the left mainfold, and you should be in business |
Hello, thanks for the quick reply.
I have the advance connected to the left side of the carb but for some reason the advance stays at around 16-20° rather than dropping back at idle, would this not cause damage if left like this. Would changing to a single vac port canister make any difference. |
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raygreenwood
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Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Fri Nov 26, 2021 8:46 am Post subject: Re: Type 4 , timing is slow to retard. |
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| Alstrup wrote: |
Hello.
The W engine did not come with dual vacum distributors, but since you are detuning it with bus carbs you simply have to take vacum from the left mainfold, and you should be in business |
Yes and no!  ......it did come with dual vacuum distributors in 411 cars and some 914 in the US in 1971 and 1972 ......but......with D-jet fuel injection ONLY.
Conversely.....and most probably to your statement .....twin carbs would have probably never had dual vacuum on 411/412/914....there were "0" imported 411/412 or 914 in the US with twin carbs (only gray market imports from Canada and Europe).
The bus 1.7L had twin carbs but was really a very different engine in tuning.....and I have no idea if it had a vacuum retard.
My point......if the engine he is using in his bay window bus is a "W" series.....it is not from a bus and could have very easily come with a dual vacuum distributor.
It is because of these things that people get all kinds of crazy combinations by accident! 
Ray |
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mikedjames
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Joined: July 02, 2012
Posts: 2736
Location: Hamble, Hampshire, UK
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| Posted: Fri Nov 26, 2021 11:43 am Post subject: Re: Type 4 , timing is slow to retard. |
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Are you sure you have the engine idling at the right speed - if the idle is over about 1000 rpm you get the centrifugal advance coming in, causing extra timing at "idle" . Then it collapses back to 850rpm and 8 degrees eventually, or just after starting . .
That can be an air leak or the throttle plates not closing or the idle volume screw set high, or the effect of a fast idle throttle setting..
Does the advance drop rapidly to 7 degrees if you pull the vacuum hose off the distributor at idle ?
It should not be sucking too much vacuum at that point so leaving the hose open should not cause too much air leakage.
This hang up could be the vacuum advance plate in the distributor being sticky - if you suck on a piece of hose attached to the distributor advance capsule, and then release, does the plate with the points on move smoothly and smartly back to zero ?
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Vanapplebomb
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Joined: November 03, 2010
Posts: 5410
Location: Holland, MI
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| Posted: Fri Nov 26, 2021 11:46 am Post subject: Re: Type 4 , timing is slow to retard. |
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| Scrapefest wrote: |
I have a W code 1700 type 4 engine in a baywindow . I have recently refitted PDSIT carbs and a vac advance distributor with dual vac ports. I cannot see where to attach the retard side of the vacuum canister to so at the moment it is just connected on the advance side. And is timed at 7° at idle max 30° ( vac hose disconnected) .
The problem I am having is with the vac advance connected after I rev the engine and let it return to idle, the timing hangs at about 16-20° . If I rev it without the vac advance the timing drops back to 7° quickly.
I have closed the throttle plates to make sure there is no vac advance at idle.
Does anyone have an idea of how to stop the vacuum from causing the timing to hang. |
Two problems here…
1) the retard needs to be connected to manifold vacuum, not ported vacuum like the advance. Original PDSIT carbs have two ports. One below the throttle plate (retard) and one above (advance). Aftermarket carbs do not have the manifold vacuum port for retard, and the throttle body progression drilling’s are not designed to play well with retard. Which do you have? Bus carbs, or aftermarket PDSIT?
2) Throttle plate too far open. The bus carb setup does NOT tolerate much throttle plate opening at idle. That advance port is right on the cusp on the closed throttle plate. The throttle should be gapped around 0.004-0.008 inches. I find 0.004 - 0.006 inches to be the sweet spot, 0.008 is dangerously close to exposing the ported vacuum advance. Any more than that and you start pulling vacuum advance. Idle speed on bus carbs is NOT set with throttle gap. It is set with the central idle circuit. Any attempt to set idle speed with the throttle plates will cause you nothing but headaches.
Once you understand how bus carbs work, they are pretty slick. BUT, everything MUST be right in order for them to play nice. If anything is not correct, it will cause you a massive headache. But once right, which isn’t hard to do, they are a super nice driving carb. Not a performance carb by any means, but just a really nice smooth driving carb.
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1800 Type 4 Berrien 295
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Alstrup
Samba Member
Joined: July 12, 2007
Posts: 7214
Location: Videbaek Denmark
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| Posted: Fri Nov 26, 2021 11:51 am Post subject: Re: Type 4 , timing is slow to retard. |
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| raygreenwood wrote: |
| Alstrup wrote: |
Hello.
The W engine did not come with dual vacum distributors, but since you are detuning it with bus carbs you simply have to take vacum from the left mainfold, and you should be in business |
Yes and no! ......it did come with dual vacuum distributors in 411 cars and some 914 in the US in 1971 and 1972 ......but......with D-jet fuel injection ONLY.
Conversely.....and most probably to your statement .....twin carbs would have probably never had dual vacuum on 411/412/914....there were "0" imported 411/412 or 914 in the US with twin carbs (only gray market imports from Canada and Europe).
The bus 1.7L had twin carbs but was really a very different engine in tuning.....and I have no idea if it had a vacuum retard.
My point......if the engine he is using in his bay window bus is a "W" series.....it is not from a bus and could have very easily come with a dual vacuum distributor.
It is because of these things that people get all kinds of crazy combinations by accident!
Ray |
The curse of variation on the models continent to continent  I stand corrected.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Fri Nov 26, 2021 12:12 pm Post subject: Re: Type 4 , timing is slow to retard. |
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| Alstrup wrote: |
| raygreenwood wrote: |
| Alstrup wrote: |
Hello.
The W engine did not come with dual vacum distributors, but since you are detuning it with bus carbs you simply have to take vacum from the left mainfold, and you should be in business |
Yes and no! ......it did come with dual vacuum distributors in 411 cars and some 914 in the US in 1971 and 1972 ......but......with D-jet fuel injection ONLY.
Conversely.....and most probably to your statement .....twin carbs would have probably never had dual vacuum on 411/412/914....there were "0" imported 411/412 or 914 in the US with twin carbs (only gray market imports from Canada and Europe).
The bus 1.7L had twin carbs but was really a very different engine in tuning.....and I have no idea if it had a vacuum retard.
My point......if the engine he is using in his bay window bus is a "W" series.....it is not from a bus and could have very easily come with a dual vacuum distributor.
It is because of these things that people get all kinds of crazy combinations by accident!
Ray |
The curse of variation on the models continent to continent I stand corrected. |
Oh man....no kidding! As much as I ....."think"...... I know about type 4 "CARS"......I am frequently surprised at how little I ACTUALLY know about the European versions of these cars.....and even more.....the region to region differences within Europe!
I get surprised all the time!
Ray |
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Dale M.
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Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Fri Nov 26, 2021 2:25 pm Post subject: Re: Type 4 , timing is slow to retard. |
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Best place for dual diaphragm distributor is in garbage can......
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Scrapefest
Samba Member
Joined: May 23, 2005
Posts: 34
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| Posted: Sat Nov 27, 2021 3:28 am Post subject: Re: Type 4 , timing is slow to retard. |
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| Vanapplebomb wrote: |
[b]Two problems here…[
1) the retard needs to be connected to manifold vacuum, not ported vacuum like the advance. Original PDSIT carbs have two ports. One below the throttle plate (retard) and one above (advance). Aftermarket carbs do not have the manifold vacuum port for retard, and the throttle body progression drilling’s are not designed to play well with retard. Which do you have? Bus carbs, or aftermarket PDSIT?
2) Throttle plate too far open. The bus carb setup does NOT tolerate much throttle plate opening at idle. That advance port is right on the cusp on the closed throttle plate. The throttle should be gapped around 0.004-0.008 inches. I find 0.004 - 0.006 inches to be the sweet spot, 0.008 is dangerously close to exposing the ported vacuum advance. Any more than that and you start pulling vacuum advance. Idle speed on bus carbs is NOT set with throttle gap. It is set with the central idle circuit. Any attempt to set idle speed with the throttle plates will cause you nothing but headaches.
Once you understand how bus carbs work, they are pretty slick. BUT, everything MUST be right in order for them to play nice. If anything is not correct, it will cause you a massive headache. But once right, which isn’t hard to do, they are a super nice driving carb. Not a performance carb by any means, but just a really nice smooth driving carb. |
Can I connect the retard side to the balance tubes that run between the carbs.
I did adjust the throttle plates so there was no vac advance at idle, and have been tuning the carbs with the central controls on the left carb.
It does look like the engine originally came with fuel injection there are no studs to mount a fuel pump on the case, the injection parts are long gone. The camper came with a receipt for an engine rebuild but it hasn't details of engine parts beyond 'Pistons' etc. So I don't know the spec of the engine.
It will be Monday before I can look at it again, I will see if I can get any numbers from the carbs.
Thanks |
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Vanapplebomb
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Joined: November 03, 2010
Posts: 5410
Location: Holland, MI
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| Posted: Sat Nov 27, 2021 6:27 pm Post subject: Re: Type 4 , timing is slow to retard. |
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What is your location? I am operating under the assumption that you are from the States. All United States dual PDSIT carbs originally had two ports. Are you outside of the States?
…You can Tee it into the balance tube… but what happened to the port on the carburetor?
If you Tee into the balance tube, you will have a vacuum leak at the carburetor that needs to be plugged. Did the brass fitting fall out of the carburetor body? If so, the opening left behind must be plugged, or your drivers side carb will be sucking air through the unused port.
From the factory, there was no port on any of the balance tubes specifically for retard. However, if you are not using one of the ports, such as the preheat vacuum port for the warm air intake, you could plum the retard there. It is close enough to the same size that the hose should push onto it.
Suggest you farmiliar use yourself with the connections. I think you are missing something. The drivers side carb (the one with the central idle circuit) will have two vacuum takeoff ports…
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Scrapefest
Samba Member
Joined: May 23, 2005
Posts: 34
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| Posted: Sun Nov 28, 2021 2:48 am Post subject: Re: Type 4 , timing is slow to retard. |
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Ok, I am in the UK, the bus is a 1972 Westfalia that was imported from the USA . At some stage before it left the US the engine was rebuilt, maybe this is when it got the W code engine , I think it was setup using PDSIT carbs when it came into the UK.
When I bought it, it had twin Weber IDFs and an 009 which gave pretty awful fuel economy.
Now it is time to sell the camper I thought going back to PDSIT carbs and vac advance would be less hassle, for the new owner . I have pieced together the stock air filter system but I am missing the warm air pre heat part so there is a small port on the balance tube free.
Is there any chance you can post a photo of the retard port on the carb , I have looked over several carbs and can't see it. I have searched but cannot find a clear picture. |
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Dale M.
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Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Sun Nov 28, 2021 7:53 am Post subject: Re: Type 4 , timing is slow to retard. |
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Put the 009 back in it, the distributor has very little to do with fuel economy....
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"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
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raygreenwood
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Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sun Nov 28, 2021 8:26 am Post subject: Re: Type 4 , timing is slow to retard. |
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A recap here for a second:
| Quote: |
I have a W code 1700 type 4 engine in a baywindow . I have recently refitted PDSIT carbs and a vac advance distributor with dual vac ports. I cannot see where to attach the retard side of the vacuum canister to so at the moment it is just connected on the advance side. And is timed at 7° at idle max 30° ( vac hose disconnected) .
The problem I am having is with the vac advance connected after I rev the engine and let it return to idle, the timing hangs at about 16-20° . If I rev it without the vac advance the timing drops back to 7° quickly.
I have closed the throttle plates to make sure there is no vac advance at idle. |
And:
| Quote: |
Ok, I am in the UK, the bus is a 1972 Westfalia that was imported from the USA . At some stage before it left the US the engine was rebuilt, maybe this is when it got the W code engine , I think it was setup using PDSIT carbs when it came into the UK.
When I bought it, it had twin Weber IDFs and an 009 which gave pretty awful fuel economy. |
The second quote...and the odd mis-match of the case # code....say that there are a handful of details that should be looked at.
As I noted....the W series is not a bus engine. That being said, if it was actually "rebuilt"...and not just swapped in as a unit.....it would not make a difference. Aside from small casting details early to late....a type 4 case is a type 4 case.
However.....if the engine was just swapped in from one of the cars that originally had a "W" series case and nothing was really changed ...or it was rebuilt to common "W" series factory spec's.....then you have high compression and a camshaft that is nothing like what a bus came with.
And while I get where Dale M is coming from.....yes....the distributor can make a huge difference in gas mileage on type 4 engines. If the advance kicks in at the wrong time time or not enough....you end up having t put your foot into it too much.
Type 4 dual vacuum distributors are also mechanical advance. The vacuum advance is mainly just a transition to bridge from idle condition to onset of mechanical. But...it commonly also has an issue with reestablishing advance at higher rpms. The retard is simply a cancellation of vacuum advance input at any rpm when the throttle snaps closed.
You still have the mechanical advance operating....so which distributor you have is critical to good running.
Even with the best quality old school German 009's....they pretty much run like shit across the board on type 4....with stock cams. The curve and more importantly advance RATE and cut in point on type 4 distributors is quite a bit different.
The dual vacuum can....depending on which original type 4 engine set up we are speaking of....injection or carbs....was also very different. While the retard function was a response in support of emissions.....how it was implemented in the rpm curve has a lot of effect on how it runs.
There were 11 different dual vacuum cans (just that I have counted and I am sure I have not seen them all) used on type 4 engines across the spectrum from 411, 412, 914 and bus.....I do not think I even know all of the bus cans.
Its also most possible as others have mentioned ....that your particular set up might run better without the retard.
One thing that will help to understand what you have....is the number off the distributor and the number stamped on the advance can arm.
Ray |
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Vanapplebomb
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Joined: November 03, 2010
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Location: Holland, MI
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| Posted: Sun Nov 28, 2021 8:57 am Post subject: Re: Type 4 , timing is slow to retard. |
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I can snap a pic tonight.
It is a pretty obvious port, so there is a good chance that the nipple came out or you have carbs not setup for retard.
I’m not a European engine accessory expert, so I don’t know how they were setup across the pond. I have seen pictures of supposedly stock euro engines that were not set up for retard, so perhaps the carbs are European, fitted after it was imported from the United States.
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Scrapefest
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Joined: May 23, 2005
Posts: 34
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| Posted: Tue Nov 30, 2021 2:59 pm Post subject: Re: Type 4 , timing is slow to retard. |
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Ok, thanks for all the suggestions, I had another look at it today.
Is the angled boss where the retard port would normally be.
Going over the carbs and linkage I found there was a small amount of pressure on the linkage just holding the throttle plates open causing the advance to stay at around 15° . I have fixed it now so when it drops back to idle the advance also drops back quickly.
Looking at the arm of the vac can it is numbered 2739
I have just connected the advance side as I am presuming the carbs don't have the retard port. |
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oprn
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Location: Western Canada
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| Posted: Tue Nov 30, 2021 3:46 pm Post subject: Re: Type 4 , timing is slow to retard. |
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| Dale M. wrote: |
| Put the 009 back in it, the distributor has very little to do with fuel economy.... |
The only proper place for a 009 is in the garbage can.
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Vanapplebomb
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Joined: November 03, 2010
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Location: Holland, MI
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| Posted: Tue Nov 30, 2021 7:09 pm Post subject: Re: Type 4 , timing is slow to retard. |
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Sorry It took so long to get back to you.
Yup, those are not drilled for retard, and not the carbs originally fitted to that bus when it was delivered to the USA. I suspect that those are euro carbs that were dug up after it was imported into the UK.
This is a US spec throttle body that I ripped in half on a bandsaw… yeah it’s an ugly hack job, I know. It shows the location of the retard nipple, and the port “R” drilled into the throttle body just below the throttle plate. Non retard throttle bodies were set up slightly differently. The advance port is higher up, as are most of the 1st progression holes I have seen. Idle mixture screw and port are the same location across all models I have seen.
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Scrapefest
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Joined: May 23, 2005
Posts: 34
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| Posted: Tue Dec 07, 2021 4:03 pm Post subject: Re: Type 4 , timing is slow to retard. |
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| Vanapplebomb wrote: |
Sorry It took so long to get back to you.
Yup, those are not drilled for retard, and not the carbs originally fitted to that bus when it was delivered to the USA. I suspect that those are euro carbs that were dug up after it was imported into the UK.
This is a US spec throttle body that I ripped in half on a bandsaw… yeah it’s an ugly hack job, I know. It shows the location of the retard nipple, and the port “R” drilled into the throttle body just below the throttle plate. Non retard throttle bodies were set up slightly differently. The advance port is higher up, as are most of the 1st progression holes I have seen. Idle mixture screw and port are the same location across all models I have seen.
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Thanks for the pictures, none my selection of carbs have that retard take off. The carbs I am using had short manifolds so I presumed they had come with the W code engine.
Looking at the receipt for the engine rebuild , it includes new heads and b&ps so I guess they were bus spec as I also found a rolling road Dyno readout from when it had IDFs fitted and made a heady 66hp .
It looks like I need to have another look at setting up the carbs as it doesn't seem to be too good in mid range RPMs or am I asking too much to be in 4th gear at 30mph on flat ground. |
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Vanapplebomb
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| Posted: Tue Dec 07, 2021 4:54 pm Post subject: Re: Type 4 , timing is slow to retard. |
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Your going to absolutely fry your engine trying to drive that slow in 4th gear.  Keep those revs up! You can’t cool the engine under load if your fan isn’t moving air.
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