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Davy_B.
Samba Member
Joined: July 27, 2022
Posts: 62
Location: België
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 Posted: Tue Mar 18, 2025 1:48 pm Post subject: Re: Pdsit 32/34 fine tune... |
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Okay.
I will be checking this! Tnx |
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lil-jinx
Samba Member
Joined: August 14, 2013
Posts: 1513
Location: New Brunswick,Canada
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germansupplyscott
Samba Member
Joined: May 22, 2004
Posts: 7235
Location: toronto
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| Posted: Tue Mar 18, 2025 4:54 pm Post subject: Re: Pdsit 32/34 fine tune... |
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| Davy_B. wrote: |
Ok so if I remove retard when i'm at 2000rpm it should not change on the Strobe.
But when i remove vac advance I should go down at 2000rpm. |
YES 100%. Retard must not (it functionally can't really but anything is hypothetically possible) be affecting the timing at any other throttle position than throttles closed (idle).
The retarded timing is only designed into the system to allow the engine to idle cleanly. With a carb setup with two throttles feeding 2 cylinders each, the engine will idle mostly only on the left carb unless the timing is super retarded (and unless there is a circuit between the left and right carb for idle charge). Without the retarded timing the engine will run fine at all throttle openings but will not idle well. The central idle circuit requires the retard to work.
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Davy_B.
Samba Member
Joined: July 27, 2022
Posts: 62
Location: België
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| Posted: Wed Jun 04, 2025 11:12 am Post subject: Re: Pdsit 32/34 fine tune... |
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| "Okay, time to blow off the dust... After a few short rides, it became clear that there was already too much play on the left throttle valve again. And this after a rebuild, unfortunately... I sent everything back to the companyâthought it would be a quick fix! Unfortunately, they came back and a part around the throttle shaft had broken off. So I sent it back again, and now they seem okayâI thought! But after a closer look, I noticed there was a gap between the two halves, both left and right. This became clear when I used a thinner gasket. Iâve now leveled them myself using a glass plate and 320 wet and dry sandpaper. Letâs hope weâre almost there now... Iâll put them back on soon, check the levels, and readjust everything. Bit of a bummer, but I guess thatâs just how it goes sometimes..." |
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orwell84
Samba Member
Joined: May 14, 2007
Posts: 2759
Location: Plattsburgh, New York
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| Posted: Today 5:42 am Post subject: Re: Pdsit 32/34 fine tune... |
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| I have been running my PDSIT carbs without the retard end of the vac can hooked up. It doesnât seem to affect the idle and Iâm certain that itâs idling on the central idling system. Of course, the timing at idle is more advanced compared to the stock setting. I have also run it with a good quality German 009. It also idled well with this distributor. |
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wagen19
Samba Member
Joined: November 16, 2007
Posts: 557
Location: germany
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| Posted: Today 6:55 am Post subject: Re: Pdsit 32/34 fine tune... |
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| Davy_B. wrote: |
| "Okay, time to blow off the dust... After a few short rides, it became clear that there was already too much play on the left throttle valve again. And this after a rebuild, unfortunately... I sent everything back to the companyâthought it would be a quick fix! Unfortunately, they came back and a part around the throttle shaft had broken off. So I sent it back again, and now they seem okayâI thought! But after a closer look, I noticed there was a gap between the two halves, both left and right. This became clear when I used a thinner gasket. Iâve now leveled them myself using a glass plate and 320 wet and dry sandpaper. Letâs hope weâre almost there now... Iâll put them back on soon, check the levels, and readjust everything. Bit of a bummer, but I guess thatâs just how it goes sometimes..." |
Please don´t take me wrong.
I hope you can find the perfection, you are trying to find.
First, I´m wondering what kind of engine and carbs you have installed, because the GD is 2,0 l with Bosch L-jet. The distributer 021 905 205 E is from 1700 ccm CA dual carb engine.
Your carbs and linkage look more 1,8 l or 2,0 l which used the 021 905 205 P Distributor with SVDA. So, imo the set up is a bit unclear and not original.
When I´m reading old car magazines of the early and mid 70ties, The testers had found out, many of these cares did not run perfect under all circumstances of temperature and load. Not even the ones with early systems of electronic fuel injection.
A dual carb system only works perfect, when the air flow on both butterflies and throttle linkage works perfectly synchron and also the beginning and volume of the acceleration system. The bus has the central idling system in left carb and also 1 screw in each carb, so in total 3 + 1 adjusting screws influencing idle and partial load.
The value of CO emission should be in the range of 2% up to 4 %.
The next thing is the mechanical resistance of the ground plate inside the distributor for vacuum advance. Sometimes a drop of oil to the splitted shaft of distributer can make a difference. Even if all single parts are in factory tolerance, the sum of tolerances in the whole system make the system a perfect GO or NOT. (Murphys Law!)
Imo, we, you should not expect too much of a more than 50 year old rather difficile and already emission controlled system. New modern cars are a different world!
Do you know a really perfect runnig original dual carb bus, the same model and carb-dizzy-set up like yours for reference?
(when I drive my 49 Standard with it´s early post war 26 VFI Huf carb, with hand choke, but without acceleration pump, I´m positivly impressed, how good and smooth that old system still works, including 6 Volts and the original, but rather low voltage and weak "star" coil) (Fuel is allways modern E 10 without any extras) |
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Davy_B.
Samba Member
Joined: July 27, 2022
Posts: 62
Location: België
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| Posted: Today 12:34 pm Post subject: Re: Pdsit 32/34 fine tune... |
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He just needs to run smooth and safe â not chasing perfection here, especially knowing not everythingâs original.
I leveled the carbs on a glass plate and cleaned up all the imperfections. Float height is set at 13mm for now â weâll see how that holds up. Everythingâs back together and the carbs are synced at both idle and high RPM. Planning to go over the rest tomorrow and double-check
everything. |
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