any one running a 34 pict carb with bigger venturis

[spencerfvee]

you got me thinking. i think your right. if i would go to a 32mm venturi it would slow the intake velocity down . i think thats why i have to run a 155 main jet. i allso kept the intake ports on the head small to help velocity and i allso did not open the ports up to big . on the end castings and the intake manifold tubes are real close to stock size i allso have the CR at 9 1/2 to help velocity . your right a booster ventri would be great . but would take a lot of room up it would have to be made out of something real thin like brass shim stock . if one could use a booster venturi from a kadron carb . i know they have low heat welding rods that they sell at swap meets that i have used in the past to weld sheet alum. and i have used it on a intake end casting to weld a hole up . i think it can be used on carbs . some thing i will have to look into your why i like samba. people like you give great imput allso could you post your data on your flow simulations for the 34 pict carb i very much would like to se them spencerfvee

[yellow73kubel]

That brings up a good point, do any any of y'all have experimental data for these carburetors? Manifold vacuum off of a few different engines would help a lot. Tubing size, engine displacement, and compression ratio would all be handy. Obviously there's more to it, but lets start simple.

I found all of my simulations last night. When I have some free time this week, I'll get them done and post the results. I do need to work through my calculations again since I lost the original ones.

My calculations are based on the maximum vacuum at the manifold on my engine. Using a simplified version of the Bernoulli principle and a few assumptions, I came to the conclusion that a stock ~1600 creates enough suction for 105m/s air velocity at that point. The simulations work their way "up" from there, yielding the maximum velocity and flow rate at the fuel outlet.

The first useful test was that pulling the venturi out yields a 13% decrease in flow velocity (213m/s down to 183m/s) with a 41% increase in flow area (539mm^2 to 907mm^2). That's what Motor is seeing in his 1904.

[spencerfvee]

hi i just posted pitchures of my motor and bug in the gallery under bug-super beetle if you want to see the motor thanks spencerfvee...........................

[NewTechnicIan]

Bumping from forever ago!
Anyone know where to get a bigger venturi for a Solex 34 Pict 3? I'm looking to keep the single carb for a while on my 1776 build and would love advice on the size I should go for.
Ian
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My 73 Standard build - It's painted! It drives under its own power! Time to get it wired and upholstered!

My 1679 Engine build.

[aryue]

Ian - there are two ways to go - if you don't have access to a nice shop or care to really take apart the carb.

Blackline Racing in Murray, Utah will remove, ream out and re-install the venturi for a little over a hundred bucks. Phone:(801) 747-3342 9AM to 6PM Mountain time.

or

You can buy one already done - http://vwparts.aircooled.net/Super-Stock-34-PICT-3-34-3-Carburetor-12V-Bocar-p/super-stock-34-3.htm

My build is described in a previous thread below:

http://www.thesamba.com/vw/forum/viewtopic.php?t=5...p;start=20

- Andrew in Austin, TX -
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OldandSlow - but still chuggin.
http://www.ph.utexas.edu/~yue/VW/VWBus.html

[vwsb74]

Or you can wrap a drillbit with sand paper. Drill it till it gets thin. Don't remove the Venturi .
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74 super beetle
2011 ford explorer traded
2010 mazda 3 hatchback
2014 Honda odyssey
2180cc 48IDA clone
Xr310 cam =171hp@6k rpm sold so as the car😢

[NewTechnicIan]

Sounds good guys! I've been having such a lively debate with myself whether or not to go 1776 or just 1641 and the carb seems to be the biggest challenge. Everyone has an opinion one way or the other on that.
If I go 1776 I'll want to make my current carb work for a while and probably go to duals after a year or two of driving and enjoying. I'd prefer while I'm cracking the case to make room for power and then wait to bolt on the parts that will let all that power out a little later on.
Thanks!
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My 73 Standard build - It's painted! It drives under its own power! Time to get it wired and upholstered!

My 1679 Engine build.

[honeybeetle]

[Paul.H]

I put a stock carb on a 1600 dp with Scat C20 cam and it was pretty quick but it needed a lot more fuel at idle to make it work and pumped out a lot of fumes. Also an engine builder I used to supply parts to said anything more than an Engle 100 would't idle properly and would be unacceptable to the customers I actually supplied him cams milder than E100 before supply dried up.
How is the idle quality with these overbore carbs , larger displacement engines and aftermarket cam ?? .

[TheViking]

Just sayin


Link

[vespist]

Bigger standard carbs!!

http://ahnendorp.com/ or B.A.S are selling new pict 34 carbs that are bigger, 37 + 39 mm.

https://www.ahnendorp.com/VW-Kaefer-Typ-1-Motorent...-2149.html

[pharos]

[Lingwendil]

This seemed like a good place to post this, since I just found it. Here's someone that modified a 34-3 to use a kadron booster venturi up at the discharge nozzle. The original llink is dead so here's the Wayback link-

https://web.archive.org/web/20150426141640/http://www.flat4ever.com/34-pict-3-mod-t46887.html

Thought this was interesting, and I may eventually want to try it on a stock-ish build.
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73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[Alstrup]

Yes. This mod works very well with turbo (blow thgrough) and or running w.o. venturi. But you need some displacement "down under" to exploit it. A "simple" big big bore Solex can easily supply enough air for 120 hp. A stock 34 w.o. venturi can too, but the jetting is a challenge. also the ignition almost has to be programmable if you want a decent result. And you don´t have to buy the overprized units from BAS. There are other options.

As a comment to Paul´s old comment on cams. As I have stated many times elsewhere, if you want to use stock carb or modified stock carb induction the W cams are NOT what you want. The engines can be tuned to work fair, but the lower rpm range will always suffer. The milder Scat cams - soso. The pre 2002 C25 was quite good, the latter a little more troublesome. CB has a range of standard cams that work really well, so does Pauter and also Steve Long.
The more displacement the easier it is (naturally) to get some air speed into the manifold at idle, but on sub 2 liter engines I can make a stock carbed or modified carbed engine idle dead steady at approx 875 and still pull just around 100 hp at 4800 rpm. I have a 125ish hp 2165 in the bench right now that idles steady at 800 rpm. As the saying goes, and it really makes sense here: its ALL in the combo.
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