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vamram 
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Joined: March 08, 2012
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Location: NOVA
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 Posted: Thu Apr 27, 2023 1:07 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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| 63vdubbug wrote: |
| kreemoweet wrote: |
It's quick and easy to throw a rivet in the throttle plate hole. If that doesn't do the trick, it's also
quick and easy to remove it. I have SVDA dist., and I completely blocked hole in 34 PICT-3 plate with rivet, best thing I ever did. Carb always adjusts perfect now, had endless problems before. |
Appreciate the response, Kreemoweet. The distributor and carb isn't on the car yet. Yours is completely sealed off? does the rivet protruding on the throttle plate causes any issues? |
I was wondering about the rivet protruding as well. Do you remove the throttle plate to install it?
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JeffL
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Posts: 1370
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| Posted: Thu Nov 23, 2023 5:40 pm Post subject: |
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| mnussbau wrote: |
| keifernet wrote: |
| Gariack wrote: |
| Anyone know the diameter of the different size holes in the throttle plate on the 34 pict carbs. |
The DVDA is approx 5/32" and SVDA is 1/8".
Hard to believe that difference does anything but trust me... it makes a big difference in the way the carb runs/tunes when your using a DVDA flange # German carb meant to be timed at 5 ATDC with an SVDA timed at 7.5 or an 009 timed at 10 BTDC.
I find the pop rivet easier than taking the plate out and soldering the hole shut, grinding it flush and re drilling it but that's a personal choice. It can also be "undone" in a matter of minutes if someone wants to go back to a DVDA and does not alter the carb in any other way. |
Sorry to bring this old thread back, but my 34Pict3 and SVDA combination is stumbling and I think it's because the carb is meant for a DVDA. I'm going to try the rivet trick. What size rivet is the right one? Also, I assume I've got to remove the center of the rivet after installation? |
Very interesting. Having issues tuning my 73 Thing with DVDA dist and stock 34 PICT 3 carb with the 181 tag. Did a carb rebuild after checking points and plugs. Had a base of carb vacuum leak and corrected.
I was trying to run it today, just got the Thing last week from an owner that did not drive it much, at 7.5 btc and only one vac hose to the advance.
Maybe the large port is my issue. I will try the factory setup tomorrow with 5atc and both hoses connected when doing timing.
Will idle when fully warm (but higher rpm to keep running with mixture screw not throttle arm) but does not speed up smooth, maybe some minor back fires. Accelerator circuit is working fine. When removing top fuel level looks good.
I looked for other vacuum leaks and will also do that again.
11-24 Update
Seems the fuel shutoff valve stopped working in the midst of my carb setup part 056 129 412
Let’s see how we do once we find one and install it.
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ashman40
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Joined: February 16, 2007
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Location: North Florida, USA
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| Posted: Fri Nov 24, 2023 9:40 am Post subject: |
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| JeffL wrote: |
11-24 Update
Seems the fuel shutoff valve stopped working in the midst of my carb setup part 056 129 412
Let’s see how we do once we find one and install it. |
If you mean the idle cutoff solenoid in the carb has failed… remove it and clip off the large plunger end from the skinny shaft. This large end plugs fuel flow to the idle circuit when power is cut. This prevents the engine from running on after the ignition switch is turned OFF. Reinstall the disabled solenoid into the carb.
This is a temp fix until you can get a replacement. You might experience “engine run on” after the key is turned OFF. If so, just step on the brakes, put the car into gear and release the clutch to stop the engine. This typically only happens with very hot engines.
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'67 Beetle #1 {project car that never made it to the road  }
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JeffL
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| Posted: Fri Nov 24, 2023 12:59 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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Thanks, I have now clipped that end off and have ordered another idle cutoff solenoid.
Well, did not find any vacuum leaks.
I tried to set up the carb and dist with the two vacuum lines for the full DVDA setup and could not get it idle. After an hour I stopped this path.
I decided to clean the carb again and plug the hole in the throttle plate as suggested with a pop rivet. Then I set the timing up for 7 1/2° btdc andused one advance vacuum line. I was able to get it to idle nice without much effort.
The oil was just changed but now was above the top line. Maybe as I was doing the set up the last 2 days I had a lot of extra fuel get to the crank case so I’ll change this later today.
During the drive idle and low speed response was OK but when I tried to get higher throttle response, it really seemed like it didn’t have power and was bogged down. I adjusted the air bypass a couple times just to see if it would run better, but it didn’t.
I did use a timing light but maybe next trip I’ll add a little more advance. The timing advances when I increase roms in the garage so I believe the advance is working but maybe not at the high end.
At the end of my road test the volume screw was one turn out and air bypass 4 1/4
Any thoughts here?
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ashman40
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Location: North Florida, USA
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| Posted: Fri Nov 24, 2023 3:25 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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| JeffL wrote: |
I tried to set up the carb and dist with the two vacuum lines for the full DVDA setup and could not get it idle. After an hour I stopped this path.
I decided to clean the carb again and plug the hole in the throttle plate as suggested with a pop rivet. Then I set the timing up for 7 1/2° btdc andused one advance vacuum line. I was able to get it to idle nice without much effort. |
Sounds like your distributor vacuum retard is not working. Try this test:
As you described, your engine should be idling @7.5BTDC now with just the vacuum advance connected.
At warm idle, disconnect and plug the vacuum advance hose at the distributor. The idle timing should not change. Leave the hose disconnected+plugged for the next test.
With your timing light, confirm as you increase the engine rpms the timing advance increases. This is the mechanical advance. You want to get an idea how much is the mechanical advance increasing the timing advance. Ideally, mechanical advance alone should increase your timing advance to around 28-32BTDC total, but no further. Any mechanical advance above this and you start getting into detonation at higher rpms under load.
Drop your engine back to idle and confirm it is still showing 7.5BTDC. Find which port on your carb has strong vacuum at idle (usually upper left rear facing port). Connect the vacuum advance hose to this port and measure how much the timing has advanced over the idle 7.5BTDC. The vacuum advance should provide 8-12deg of additional timing advance.
Disconnect and plug the vacuum advance hose. Connect the distributor vacuum retard port to the strong vacuum port of the carb. You should see the timing change to around 5ATDC (-12deg of advance). This confirms your vacuum retard is functioning normally.
I suspect you will find something not working correctly with your vacuum retard system? This is not uncommon for the 40+ yr old DVDA distributors. No problem. Just leave the vacuum retard disconnected and run your DVDA as an SVDA. The only real reason to run the DVDA with idle retard is to comply with emission laws of your state/location. If you don't need to comply with such laws you are better off disconnecting/disabling the vacuum retard.
| JeffL wrote: |
| The oil was just changed but now was above the top line. Maybe as I was doing the set up the last 2 days I had a lot of extra fuel get to the crank case so I’ll change this later today. |
If your oil level is increasing you have a problem. This is normally caused by raw fuel draining down in to the case. Either from the mechanical fuel pump leaking down into the case from a torn diaphragm. Or from raw fuel flowing down the carb; usually from an incorrectly adjusted inlet valve/float/fuel pressure. Fuel flows down the carb into the intake and then the cylinders. The fuel leaks past the piston rings and drains into the case.
Neither is normal. Find out where the fuel is coming from.
| JeffL wrote: |
| During the drive idle and low speed response was OK but when I tried to get higher throttle response, it really seemed like it didn’t have power and was bogged down. I adjusted the air bypass a couple times just to see if it would run better, but it didn’t. |
If you actually have a fuel draining into the case problem this is likely causing your problems. Raw fuel flowing down the carb or lack of fuel pressure because the fuel pump has a leak, both will cause problem with the engine running,
The two adjustments on the left side of the Solex Pict -3 carb are Bypass screw and Volume screw. Bypass controls the amount of air-fuel bypassing the closed throttle plate at idle. This controls your idle rpms.
The Volume screw controls the amount of fuel in the Bypass mixture. Unscrew it and you get a richer idle mixture. Screw in and the mixture will be leaner.
The screw at the end of the throttle arm should be adjusted so the throttle plate is fully closed when the screw is resting on the lowest level of the fast idle cam, but you don't want the weight of the throttle spring to be carried by the throttle plate. The screw at the end of the arm carries the weight of the spring. Tighten the screw until it is just touching the lowest level of the cam, then turn in another 1/4 turn to keep the pressure off the edges of the throttle plate.
| JeffL wrote: |
| I did use a timing light but maybe next trip I’ll add a little more advance. The timing advances when I increase roms in the garage so I believe the advance is working but maybe not at the high end. |
Do this test above with the vacuum hoses disconnected to confirm the mechanical advance is working and providing the expected total idle + mechanical advance.
You can increase the idle timing but it also results in increasing the total mechanical timing advance. If your exceed 32BTDC idle+mechanical you risk detonation when accelerating at freeway speeds. Be careful.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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JeffL
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| Posted: Fri Nov 24, 2023 3:44 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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Fantastic Ashman 40 
I will drop and refill the oil. The fuel pump could be the culprit if I didn’t overfill it in the beginning (possible). It does feel like I am running out of fuel at speed and hitting the accelerator pump is noticeable. When taking the fuel line off the carb there is always pressure/fuel. I have a pressure gauge some place from setting the spring in the fuel pump for our Judson on the 56 Ghia, even had to add some gaskets as shims.
I did find my dwell meter and I was off with a 35 dwell and got it closer to 50 for the next drive. It’s an old Sears meter but seemed to work and get me Rpms too.
With a 50 year old distributor your tests sound great. I usually tear everything down. Maybe the dist is next!
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ashman40
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| Posted: Sat Nov 25, 2023 11:06 am Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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| JeffL wrote: |
| I will drop and refill the oil. The fuel pump could be the culprit if I didn’t overfill it in the beginning (possible). It does feel like I am running out of fuel at speed and hitting the accelerator pump is noticeable. When taking the fuel line off the carb there is always pressure/fuel. I have a pressure gauge some place from setting the spring in the fuel pump for our Judson on the 56 Ghia, even had to add some gaskets as shims. |
Before you drain and refill the oil… remove the mechanical fuel pump and look at the underside. It should be packed with grease. If the diaphragm is leaking it will have washed the grease down into the case and the underside of the pump will smell of gasoline. Gas should be completely contained within the upper section of the pump. If leaking, replace the pump BEFORE you change the oil. Otherwise you will again be paying for another few quarts of oil to flush the gas out of your crankcase.
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---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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JeffL
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| Posted: Sat Nov 25, 2023 12:44 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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| ashman40 wrote: |
| JeffL wrote: |
| I will drop and refill the oil. The fuel pump could be the culprit if I didn’t overfill it in the beginning (possible). It does feel like I am running out of fuel at speed and hitting the accelerator pump is noticeable. When taking the fuel line off the carb there is always pressure/fuel. I have a pressure gauge some place from setting the spring in the fuel pump for our Judson on the 56 Ghia, even had to add some gaskets as shims. |
Before you drain and refill the oil… remove the mechanical fuel pump and look at the underside. It should be packed with grease. If the diaphragm is leaking it will have washed the grease down into the case and the underside of the pump will smell of gasoline. Gas should be completely contained within the upper section of the pump. If leaking, replace the pump BEFORE you change the oil. Otherwise you will again be paying for another few quarts of oil to flush the gas out of your crankcase. |
Thanks. I was ready to pull it and wanted to do a pressure check first. The more precision gauge went over three and the cheap one I bought to see if it was pegged was just about 3. So let’s say I am running 3-4
PSI
I let it sit twice and it maintained fuel pressure for over 1/2 hour. I would think the carb needle seats well and the check valve in the fuel pump is ok. Could still be an issue but I didn’t want to change too many things at once.
I then changed then oil and saw I likely just overfilled it a little. I pured every back into the jug and it looked like I had what started with. I wanted to flush out the engine and it looked good.
When pulling the vacuum advance line and plugging carb, the timing was maintained and I could see the mechanical advance was working. At 100 pct I’m not sure but I could see it swing with the timing line and reving the engine.
Went for a drive after adjusting dwell up to 45 and about the same response (just had a hard time getting 50 so I stopped and will fine adjust later. Good idle response again but throttle response sluggish (accelerator pump is working) but top end power not good. On my ride back I’m going to move the advance from the side of the carb to the rear “full” port.
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JeffL
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| Posted: Sat Nov 25, 2023 1:02 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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Wow. This is a first for me after at least 50 air cooled VWs but maybe it’s a Thing thing.
On the way back changing the vacuum line position didn’t matter.
So next ………. I thought let’s pull the hose off to the oil bath air cleaner ……… It’s like a new car! I will have to look and see but i cleaned the screen in gas and added new oil. Acceleration is good and top speed response good.
This I’m sure could lead to pulling more fuel, unburnt fuel and some in the oil.
I am always concerned about back fires so I always run the stock air cleaner.
Thanks for all of the help and discussion! I need to work on a the air cleaner next. I did not wash the upper unit.
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ashman40
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| Posted: Mon Nov 27, 2023 8:23 am Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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| JeffL wrote: |
| So next ………. I thought let’s pull the hose off to the oil bath air cleaner ……… It’s like a new car! I will have to look and see but i cleaned the screen in gas and added new oil. Acceleration is good and top speed response good. |
Try kerosene instead. While both clean well, gasoline fumes are combustable (explosion) while kerosene is only flammable.
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AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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JeffL
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| Posted: Mon Nov 27, 2023 2:33 pm Post subject: Re: Idle problems DVDA? SVDA? 34 Pict 3 |
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| ashman40 wrote: |
| JeffL wrote: |
| So next ………. I thought let’s pull the hose off to the oil bath air cleaner ……… It’s like a new car! I will have to look and see but i cleaned the screen in gas and added new oil. Acceleration is good and top speed response good. |
Try kerosene instead. While both clean well, gasoline fumes are combustable (explosion) while kerosene is only flammable. |
Thanks, it’s just what i had and did it outside. This did not help. It was still restrictive when connected. I have to think why else this could be. Maybe the new rubber connector to the carb is too soft and compresses?
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