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JonRich55
Samba Member
Joined: April 06, 2018
Posts: 378
Location: Leesburg, VA USA
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 Posted: Wed May 31, 2023 4:41 pm Post subject: 34-3 Carb question |
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Finally have my new fuel tank, lines and Pierburg pump installed and the engine up and running. I have a correct 73 DVDA setup, though I have pulled the Retard line and set the timing at 7.5 BTDC as a SVDA.
I reatached my retard line and the timing dropped back to just about 5 ATDC as it should, though the RPMs were to low. After running it for a few mins I turned it off.
My questions is this - when I detacthed the Retard line from the Carb (I do have it routed up and through the Aircleaner to provide the hook), there was a small amount of gas that came out of the end of the hose.
Have others had gas come out after they shut the engine off on the retard line? I know that is what the hook is there to prevent damage, just dont remember ever seeming that (I might have pulled it off before it could run back down the carb).
any thoughts? |
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heimlich 
VWNOS.com
Joined: November 20, 2016
Posts: 6621
Location: Houston, Texas
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| Posted: Thu Jun 01, 2023 12:42 pm Post subject: Re: 34-3 Carb question |
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The advance side is the one that requires the hook. That is the one furthest away from the distributor. It is the smaller diameter hose.
You don't have to run your distributor with the retard line attached.
How did you set the timing as an SVDA? Was it with both hoses detached?
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sb001
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Joined: May 19, 2011
Posts: 10406
Location: NW Arkansas
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| Posted: Thu Jun 01, 2023 1:23 pm Post subject: Re: 34-3 Carb question |
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I wouldn't worry about a small amount of gas (you're sure it was gas?) coming out the end of the vacuum line. The retard port is below the throttle plate so it's quite possible a small amount entered that circuit from gas getting shot down the carb throat.
Also, where are those photos! 
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JonRich55
Samba Member
Joined: April 06, 2018
Posts: 378
Location: Leesburg, VA USA
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| Posted: Thu Jun 01, 2023 3:57 pm Post subject: Re: 34-3 Carb question |
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| heimlich wrote: |
The advance side is the one that requires the hook. That is the one furthest away from the distributor. It is the smaller diameter hose.
You don't have to run your distributor with the retard line attached.
How did you set the timing as an SVDA? Was it with both hoses detached? |
Actually, the Green line was run up at through the air cleaner clasp (on all that had the retard line) to create the same hook as the advance. They did it this was because the port exited back towards the hood and a hard line wasnt functional in that location. It still needs the hook.
I timed it with hoses off, port plugged like you would for a standard SVDA. looking at the canister specs, it looked like it had a very similar amount of advance as the SVDA, so I timed it as one. It just runs a bit better than when I have it set and timed as a DVDA (the retard side works properly). |
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JonRich55
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Joined: April 06, 2018
Posts: 378
Location: Leesburg, VA USA
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| Posted: Thu Jun 01, 2023 4:00 pm Post subject: Re: 34-3 Carb question |
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| sb001 wrote: |
I wouldn't worry about a small amount of gas (you're sure it was gas?) coming out the end of the vacuum line. The retard port is below the throttle plate so it's quite possible a small amount entered that circuit from gas getting shot down the carb throat.
Also, where are those photos! |
Most certainly, it was gas...and a very small amount. I guess this was the first time I have pulled that side almost immediately after running it. Every other time it was hours or days later.
You want a picture of the gas coming out: I will post a picture of the Bug soon...still a lot to do to really feel comfortable driving it (sitting way to long!) |
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vamram
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Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Fri Jun 02, 2023 4:38 am Post subject: Re: 34-3 Carb question |
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| JonRich55 wrote: |
| ...I timed it with hoses off, port plugged like you would for a standard SVDA....It just runs a bit better than when I have it set and timed as a DVDA (the retard side works properly). |
I don't think this is correct. A DVDA has to be timed and hoses connected, w/a timing light to 5* ATDC.
At the very least, if you do time it as a SVDA w/the hoses disconnected, once you connect the hoses you have to re-tune your carburator. The volume and air screws are not the same at idle between the SVDA and DVDA setup. That could explain why the car wants to die when you connect the DVDA port.
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 6621
Location: Houston, Texas
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| Posted: Fri Jun 02, 2023 6:17 am Post subject: Re: 34-3 Carb question |
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| vamram wrote: |
| JonRich55 wrote: |
| ...I timed it with hoses off, port plugged like you would for a standard SVDA....It just runs a bit better than when I have it set and timed as a DVDA (the retard side works properly). |
I don't think this is correct. A DVDA has to be timed and hoses connected, w/a timing light to 5* ATDC.
At the very least, if you do time it as a SVDA w/the hoses disconnected, once you connect the hoses you have to re-tune your carburator. The volume and air screws are not the same at idle between the SVDA and DVDA setup. That could explain why the car wants to die when you connect the DVDA port. |
DVDA you time with the hoses connected. You have to get the 5 degrees correct and in order to do that the hoses have to be connected.
You can also time it with the hoses disconnected like an SVDA at 7.5 or at max advance. You can leave the retard side disconnected if you do this.
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JonRich55
Samba Member
Joined: April 06, 2018
Posts: 378
Location: Leesburg, VA USA
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| Posted: Fri Jun 02, 2023 9:02 am Post subject: Re: 34-3 Carb question |
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| heimlich wrote: |
| vamram wrote: |
| JonRich55 wrote: |
| ...I timed it with hoses off, port plugged like you would for a standard SVDA....It just runs a bit better than when I have it set and timed as a DVDA (the retard side works properly). |
I don't think this is correct. A DVDA has to be timed and hoses connected, w/a timing light to 5* ATDC.
At the very least, if you do time it as a SVDA w/the hoses disconnected, once you connect the hoses you have to re-tune your carburator. The volume and air screws are not the same at idle between the SVDA and DVDA setup. That could explain why the car wants to die when you connect the DVDA port. |
DVDA you time with the hoses connected. You have to get the 5 degrees correct and in order to do that the hoses have to be connected.
You can also time it with the hoses disconnected like an SVDA at 7.5 or at max advance. You can leave the retard side disconnected if you do this. |
Vamram - That is exactly what I did. Having said that, I will need to replace the butterfly in my carb to the later '74 that has the smaller hole for better idle and off idle running (mine is the correct DVDA larger diameter one).
Heimlich - you can run a DVDA like a SVDA as long as you time it the way a SVDA is. Just plug the Retard port on the carb and leave the retard port on the can open. Most DVDA cans have dead retard functions because folks forgot to route the hose up through the air cleaner and gas ran down the line and ruined them. |
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vamram
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Location: NOVA
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| Posted: Fri Jun 02, 2023 10:05 am Post subject: Re: 34-3 Carb question |
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| JonRich55 wrote: |
....I will need to replace the butterfly in my carb to the later '74 that has the smaller hole for better idle and off idle running (mine is the correct DVDA larger diameter one).
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It won't idle right as an SVDA w/the bigger DVDA throttle plate hole. Might be easier to close up the existing hole than to disassemble and replace the throttle plate. There are threads on here w/different ways of doing that - the rivet option comes to mind.
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Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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JonRich55
Samba Member
Joined: April 06, 2018
Posts: 378
Location: Leesburg, VA USA
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| Posted: Fri Jun 02, 2023 10:45 am Post subject: Re: 34-3 Carb question |
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| vamram wrote: |
| JonRich55 wrote: |
....I will need to replace the butterfly in my carb to the later '74 that has the smaller hole for better idle and off idle running (mine is the correct DVDA larger diameter one).
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It won't idle right as an SVDA w/the bigger DVDA throttle plate hole. Might be easier to close up the existing hole than to disassemble and replace the throttle plate. There are threads on here w/different ways of doing that - the rivet option comes to mind. |
True, I have seen those threads with the options for closing (reducing it). I may look for a late 73/74 version for an Autostick that was paired with the SVDA and have Tim rebuild it (he rebuilt my current one). It is getting hard to find working Dual cans for the AS setup.
It ildes ok this way, just not as smooth as I would like it to be. |
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