Any Ideas on adjusting a carburetor on a 1974 with a 34 pict 3? its getting gas but durring acceleration it boggs down. I have blown the lines and the carb is getting gas.
Thanks Alex
Alex,
http://www.vw-resource.com/34pict3.html . Also note Rob has a "how to" on adjustment of the accelerator pump. Very crucial if you have run a 009 at any stage and gone back to an SVDA. With a 009, the pump stroke is often set at maximum to compensate for the dreaded "flat spot". Replace it with an SVDA and you have to re-set it.
HTH
Volkenstein
I'm having the same trouble with my '71. Currently setting the accelerator pump higher. I'm afraid to touch anything else.(//)
Just a quick note, Make sure that your accelerator pump nozzle (brass thing in throat of carb) is spraying fuel right at where the lower butterfly meets the carb throat. (on the side of the butterfly that goes down i'm pretty sure). If it is not pointed correctly it will wash out some. Combine that with a 009 and who knows how strong the effect would be. That brass pipe(nozzle) is easy to move on some carbs.
I found an accelerator pump brass 90 degree nozzle in a cylinder...
a couple of years ago.... lol
so, they can move easily..
009 dizzy to 28 degrees advance... [28-32]
just make a note of what you are doing...
don't depend on your memory like Me.... lol
and forget everything.... lol
cheers
LEE
Here's my adventure with the idle issue. I've been chasing this around for some time now. I got some time to troubleshoot while on vacation. Here's what I discovered. Found a vacuum leak at the air cleaner thermostatic vacuum switch. Plugged it at the manifold. The accelerator tube was pointed at the nozzle looking thing in the middle of the carb. Readjusted it to shoot down the carb throat without hitting anything. I did run into another problem. After fixing the above, I tried to reset the idle. Quit idling all together! After 2 days of trying to figure out what the hell I did, I went back to basics. Went up front to the fuel tank and found a filter under the tank that was plugged with rust. I pulled the tank, drained, cleaned the screen inside the tank, new filter, fuel line, pulled the carb and sprayed it out with cleaner, after disassembling. Put it all back together and she idles. I would recommend anyone to follow what I did from the tank back so you know you have a good fuel delivery system. My car ran fine until I tried to set the idle, I don't know what happen but making the change upset the balance. I have test drove it and is much improved. I did find a vacuum leak around the bushing on the throttle side of the carb. I'm not sure if there is a temporary fix for that until I get it rebushed. I discovered that if from a dead stop in Drive 1, if I go WOT it accels steady but if I go part throttle it wants to die. Not sure why? I still have a question about aiming the nozzle. Should it be pointed so the fuel hits the side of the carb throat or so when the plate opens it does not hit the plate? What I'm saying is, the fuel sure never hit the throttle plate. Right?
Oh, one last thing. I took the dizzy out and cleaned and lubed it, new vacuum lines. Really gummed up.
Any help with the flat spot would be appreciated.
'73 SB AS 34PICT3 SVDA Dist. 7.5º btdc
vwman,
Aim the nozzle to shoot at the point where the plate touches the venturi wall.
SVDA on a '73? Not stock.
What are the numbers on the distributor? Also, have you verified where TDC actually is? A stock '73 pulley should be marked for 5 ATDC. Does the distributor can hold vacuum?
With the throttle bushes, they will get sloppy to the point of starting to cause tuning headaches. They can be re-bushed.
HTH
Volkenstein
Quote from: volkenstein on 30 November 2008, 01:20
vwman,
Aim the nozzle to shoot at the point where the plate touches the venturi wall.
SVDA on a '73? Not stock.
What are the numbers on the distributor? Also, have you verified where TDC actually is? A stock '73 pulley should be marked for 5 ATDC. Does the distributor can hold vacuum?
With the throttle bushes, they will get sloppy to the point of starting to cause tuning headaches. They can be re-bushed.
HTH
Volkenstein
VW 043-905-205, Bosch 0231 170 034
Yes, not stock distributor. I took it off a '74 SB w/manual trans. I verified TDC and marked the pulley for 7.5º BTDC. I tested the vacuum can with a vacuum pump, tested good. I have the OG dual advance distributor. I didn't see any reason why I couldn't use the SVDA as long as I retimed it @ 7.5º BTDC.
vwman,
Distributor & timing appear good to go from what you've posted. One last check - does the mechanical advance mechanism work OK?
Hoiw are the O-rings on the two adjustment screws? Have you tried the acc pump adjustment? Hmm, have you set the thing up as per that link to Rob and Dave's site ^^^ up there? How sloppy is the throttle shaft? Too much wear and it'll idle all over the shop due to the finicky nature of a 34 Pict 3.
Regards
Volkenstein
Mechanical advance works ok, checked with timing light. O-rings on the two adjustment screws have been replaced. Used rebuild kit not long ago. Set up as per the link to Rob and Dave's site.
QuoteHave you tried the acc pump adjustment?
I'm going to do that next. My theory is that when I go WOT there is enough vacuum for the main jet to kick in. If I go part throttle the mix goes lean due to the vacuum leak at the bushing. I think if I can get a better squirt of fuel it may richen the mix up enough to fix the flat spot. As far as the idle goes, it idles at about 950-1000 rpm. And thats with the big idle screw just barely off its seat. I figure thats not how it should be but I don't know for sure, I have nothing to compare it to. Haven't seen a new Bug since the 70's. :) Is there any thing I should know about the accel pump adjust? I was going to make the stroke longer with the adjustment screw. There's a + and - on it.
Thanks Ω
I set my pump stroke at max and it made things worse! :-[
Quote from: johnr on 01 December 2008, 16:29
I set my pump stroke at max and it made things worse! :-[
Worse in what way? It floods the engine?
vwman,
Pretty much. It dumps too much fuel causing some stumbling, rather than hesitation. I found out when I went to my SVDA from the 009. Had to dial the pump stroke back to just a tad over halfway on the "+" side.
Regards
Volkenstein
Really bad stumbling. Worse than any other setting. I re-set it in the middle a little on the plus side as Volkenstein says. It works best there.