1600 DP with DVDA dist. running issues.

[speedracer89]

Hello,

I have a dune buggy with a 1600 and I have nothing but issues with.

I tried lots of adjustments and I will explain everything I have done.

The engine is a 1600 DP with a 34 pic 3 carb. DVDA distributor.

The engine had a solex 34 pic 3 carb the and ran like crap with this engine had a flat spot and was not consistent.

So I bought a new Empi 34 pic 3 carb and I am having similar issues.

The engine is running super rich on both carbs and I can't get adjustment out the them. Plugs are going black instantly after 10 seconds of running. I can't get the engine to idle on either carb. I having the timing close but that should still not prevent the car from idling I would think. I have tried the following jets 127.5 main and 130 main, idle jets 55 and 60. I have tried numerous adjust on both screw on the 34 pic 3 and no progress.

I will add a little more to the story on another carb I tried. I had a H030/31 carb laying around with the dual port intake adapter plate. I put this carb on the engine and the engine will idle but still seems to run super rich. If I hit the throttle quick I have a major flat spot in the carb. The engine stalls or almost stalls when I hit the throttle a second time revs up perfect. I can see black smoke from the exhaust and my eyes can feel the fuel in the exhaust. I have tried to lean this carb out and it does't work I tried to adjust the accelerator pump with no luck there either.

Any suggestions is greatly appreciated I have never had a engine that ad these kind of running issues.

[66brm]

Post a pic or two of how you have the distributor plumbed to the carb, what's your timing set at, and how?
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[hobbybob517]

Isn't the 34 pict-3 supossed to be combined with a SVDA dist?
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[Alstrup]

They came with both, dependant on year.
The DVDA engines are generally somewhat more difficult to get to run right. I usually convert these to SVDA. But in the O.P´s case it sounds to be a multiple issue situation. Check everything from the bottom & up. voltage to the coil, - everything.
T

[speedracer89]

[speedracer89]

[speedracer89]

[mikedjames]

Fuel pump too high pressure ?

Stock / aftermarket / Electric fuel pump?
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[74 Thing]

Crappy distributor cap-what is the quality of the rest of the ignition parts?

[[email protected]]

one issue a lot of folks aren't aware of is the DVDA is timed to 5 ATDC. To get a reasonable idle speed at that retarded timing, the carburetor must flow a LOT more air at idle. So it has a hole in the throttle plate, in addition to the normal idle circuit (throttle plate bypass).

If you install a SVDA type carb on a DVDA equipped engine, you can't get the idle speed high enough (not enough air) for the retarded timing. The solution is a hole in the throttle plate and a larger idle jet to compensate for it.

or put an SVDA on there with "normal" timing at idle, and the carb will adjust and behave properly.

New carbs are all of the SVDA type, the only DVDA ones were original, and IDed with the base stamp.

Other common causes of your plug fouling are anti-seize on the plug threads (don't do this), or too much fuel pressure. What is the fuel pressure?
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[74 Thing]

Page down on this thread and you can see the difference in throttle plate hole sizes for DVDA vs SVDA

https://www.thesamba.com/vw/forum/viewtopic.php?t=711261&highlight=hole+throttle+plate+svda+dvda

[wcfvw69]

John touched on it already. There were two main versions of the German Solex 34-3 carbs. Most were for DVDA's. In 1974 they went to SVDA distributors like the famous 043905205 or 034 SVDA in non-California markets and still ran DVDA's in California for smog reasons.

Mixing and matching distributors and carbs equals poor results and idling. ALL the aftermarket 34-3 carb copies are designed for SVDA. All the German Solex carbs have a base flange number at the bottom of the carb. It's a 4 digit number like 377-1. This tells you what the carb was delivered as (DVDA or SVDA).

The other important factor that is often overlooked is matching the correct distributor to the VW it's in. You wouldn't want to run a autostick DVDA in a manual transmission bug. Nor would you want to run a German 034 in a heavy bay bus running a type 1 dual port engine. The German Bosch distributors have different advance rates in them. Some advance quicker than others.

The DVDA distributors get a bad rap due to folks not knowing what I posted above. When you match a restored DVDA (with a good vacuum canister on both the retard and advance side) with a correctly restored German Solex DVDA carb, you get excellent results. You have to time the engines with a DVDA at 5° ATDC because you are hooking up the retard vacuum line to manifold vacuum. The advance side of the vacuum canister connects to ported vacuum. So, at idle the engine has manifold vacuum but there's no ported vacuum because the throttle plate is closed. As John mentioned you also have to adjust the carbs correctly because they do pull more air to idle at that advance timing.

I've sold a ton of restored DVDA's to folks who wanted the correct distributor on their engine as delivered new. Most also purchased the correct version of the German Solex 34-3 carb from Tim at Volkzbitz.com. Folks who install them and adjust them correctly are rewarded with wonderful driving VW's that idle like a sewing machine.
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[speedracer89]

[wcfvw69]

[Xevin]

[wcfvw69]

[speedracer89]