any one running a 34 pict carb with bigger venturis

[Alstrup]

Oh, my bad on the engine size But an interesting set up.
- The rods are not your limiting factor, unless they are worn out. Stock rods hold up to 6500 and then some. But your engine has stopped making power looong time ago by then

Its hard to say how much the larger intake valves/ports improove the charge with a stock cam. I would imagine that your peak power would be in the 4000 - 4200 rpm area. From there it flattens out for about 250 rpm and then takes a dive. I may be wrong though.

Looking forward to hear if the jet change makes the difference in your set up.

T

[Motor7710]

Testing is done on the 34 pict 3 carb and this is what I found:

1. Increasing the size of the air correction jet increases the hesitation dramatically even if you increase the main jet.
2. Increasing the main jet only, did decrease the hesitation to a barely noticeable if any.
3. Best of all, I found more PONYS! On my top end! woohoo
4. I think this mod is solved!!!!

Here are the specs for my setup on my 1904cc
Use this data to get close to your engine size and combo, then fine tune.
Idle .80mm (80mm)
Air Correction jet .60mm (60mm)
Main jet 1.65mm (165mm)
Aux jet .42mm (42)mm)
_________________
If it stopped dripping oil you’re probably out of oil!

[Motor7710]

[R.L]

hi
any advice on jetting 34pict 1776, cam 284dgr 9,5 comp cb intake
heads 40mm and 35mm valves mild port..
vintagespeed stocklooking exhaust,
i have modified the venturi to about 28,5mm
idle jet65 main jet 150 cant remember air corr jet but stock,
also where can i get a 30mm venturi if i need one?
thanks

[Alstrup]

Sounds about right. But you really CAN´T determine correct jetting without an 02 meter or a CO tester. - Well, you can, but it will take about 20 jet changes and a comprehensive datalog.

I would think that you can get a 30 mm Venturi the same place you got the 28,5

Otherwise I can supply you if needed.

T
PS. Monitor your cylinderhead temps. That muffler system is not the best in conjunction with larger exhaust valves.

[R.L]

[spencerfvee]

hi alstrup . i looked at the shop for a good used 34pict carb. but could not find one . so i bought a EMPI 34 pict carb. i have in the past not been a fan of EMPI parts . but after working on a 34 pict EMPI carb. my mind has changed .you can see pictures on samba gallery under parts / accessories bug. of what i did to the 34 pict carb ... the casting is super nice . i removed the venturi and opend the venturi up to a 30mm. i must say the venturi fit in the carb body just right. no gape . i then chamferd the discharge tube . to help pull fuel from the bowl . i then ground down the retanner plug that hold in the venturi in and used loc tite 680 topped off buy useing J B weld to seal the retanner plug . i then set the acc. gas discharg tube. so the gas from the acc. discharges tube would discharge past the leading edge of the buttfly.i would like to say that the acc. pump puts out one hell of a long pump shot of gas . that will be great to keep the motor from bogging under power . i then installed 150 main jet to start with and a 125 air jet to start with and a 65 idle. jet with a 200 needle and seat i do have a 175 needle and seat too .i plan to run a fuel reg. set at 2/1/2 lbs to start with . i will run a 5 inch stack . i would like to point out some things i found on the EMPI carb. the retaning nuts were lose on the throttle shalf . no big deal . the AcC discaharg tube was loose some thing to check on all carbs other than that carb was ok every one thanks for all the good info and alstrup for his great input on a 34pict carb. its been fun will update on air cleanner . i allso am going to used a mallory dizy set up to run 14 degs int. all in buy 2500 rpm 32 degs total spencerfvee

[Alstrup]

Good Spencer.
- The problem with the Empi 34´s was actually not the function of the carb, apart from the things you have found to be loose and the likes. More that the shaft bushings, or should we say the lack of such resulted in the carbs wearing out in notime flat.
Now for the record I have to say that I have not had a new Empi carb in my hands for at least 15 months. Things and quality may have changed. I know more people who claim that the Empi IDF´s are now at or above level with the Spanish IDF´s. (Not that the spanish are superior) But it - could - happen to be so that Empi actually makes something that works now. If that is the case, my hat is off for that.

T

[spencerfvee]

hi alstrup .i have pictures of the brass bushings on the gallery under parts/accessories bug .if you want to see them . your so right 1 year ago i had a friend who bought a EMPI 34 pict carb i helped him set it up we found that the idl. air jet did not have the right size hole to seal the rubber o ring the hole was to big i put a dellorto o ring in that was bigger . and then it worked great and your right his his shaft did wear out fast he then went to a set of kadrons .i to am happy EMPI has done something about there carbs . i bought this EMPI carb for $135.00 on line there going for $169.00 allso the new solex 34s are selling for over $200.00 i took a chance and bought the EMPI one . do you run pre heat to your intake manifold and pre heat to your carb ? my self i have never run pre heat to the above . i only drive my bug in the summer . very nice talking to you and thanks for your time spencerfvee

[Alstrup]

Around here I ALWAYS run manifold preheat. And on my std plus engines I also use airfilter preheat. If I dont I get the typical cold air problems in spring and fall.
The airfilter preheat can be left out if the customer agrees on being aware of that he most likely will experience "semi cold" problems on chilly mornings.

MOTOR, I do not really understand why you need such a large idle jet. Even on my 2007 100 hp I only have a 0,65 idle jet. But if it works it works.

T

[spencerfvee]

hi alstrup to tell you the truth i only had a 65 idl jet at home lol . i have to get back to the shop on wedsday and get a solex 60 idle jet. .i am lucky to have a friend who has a vw parts store and shop and he lets me use his shop any time. . . . i allso am going to test the carb on one of his shop motors i like useing only solex jets .i have a some jets left over from my friends formula vee racing days that he gave me years ago i dont like to use the empi jets. my motor is a 2180 with a v26 engle cam ported 40by 35 valve heads take care spencerfvee..

[[email protected]]

just to comment, changing idle jets in increments of "5" is too large of a change when you get close, it should be 2.5.
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[spencerfvee]

hi john thanks for info will do spencerfvee

[[email protected]]

for example, a change from 50 - 55 is > 20% increase in fuel.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

[spencerfvee]

hi alstrup i am going to run manifold pre heat and pre heat on the air cleaner . i found a 1971 bug air cleaner at the shop . that is in great cond. with the bigger 30mm venturi and the carb needing more air. will the 1971 air cleaner. give the carb the air it needs for a 2180cc motor that has 40 x35 valve heads a engle V26 cam i do not plan on going over 5,500 rpm . i can rework the air cleaner to flow more air . i have done this in the past . i like haveing the 5 inch stack thats built into the stock air cleaner thanks spencerfvee

[spencerfvee]

hi every one. we are haveing a heat wave today in ohio 49 degs .makeing a stock 34 pict carb with a 30mm venturi work on a vw motor has been a lot of fun .i cant wait to get the new motor into my 1971 bug . on my air cleaner . i have a 1971 cleaner. i cut the air horn back 4 " to help get more air into the carb. i all so left the pre. heater flap on the air cleaner . i did remove the second air flap . it resticked the air flow a lot . there was a edge on the air itake on the inside of the air cleaner where the air intake mates to the air cleaner houseing. i bent it over to smoth out the air flow to the air cleaner houseing . i now have pre heated air and more air to the carb . i was going to cut out the old oil bath filter and install a K&N air filter . but looks like to much work lol. if any one has installed a dry paper air filter into a stock air cleaner let me know how you did it and how it worked out . i know EMPI sold them in the 1960s but i think they only fit a 1967 air cleaner and i would not want to use one that old the paper filter breaks down over the years and falls apart thanks spencerfvee

[spencerfvee]

hi every one just a update i got the motor all together . its a 2,180cc v 26 engle cam scat rockers 1.2.1 82 crank 92mm cyls. scat rods.alum. bubble top case . i put some NOS old school parts on that were sitting around doing nothing. i cant wait to get the motor in my bug to see how the 34pict carb works with the 30mm ventura see pictures in gallery under parts/ accessories- bug spencerfvee

[yeoldeluke]

[spencerfvee]

hi alstrup . update. i got the motor built . i have the motor in my bug its a 2180 V26 cam scat 1:2:1 rockers 40 by 35 valves mild port work 82 by 92 thanks to you on your imput i got the EMPI 34 pict carb running good . i found these things wrong with the EMPI carb the idle screw had to small a rubber o ring . had to use a solex o ring . i had to lower the float by cuting off some on the tab that stops the float from going lower heres my jetting 125 air jet 155 main jet 30mm ventri 200 needle and seat 55 idle jet i set my mallory up to have 14 intal. 32 degs total all in by 2,400 rpm . the carb did not like intal. any lower than 14 degs . i ended useing 1 3/8 " header .i am running a 4 qt deep sump old school nos EMPI oil pump and filter alstrup you were not bull shitting about how well a single 34 pict carb would run on a 2180 motor . this motor shits and gets no bog . i was on the free way when rush hour was going on and i was staying with the other cars doing from 80 mph to 90 mph . this motor will go well over 100 mph if i wanted to it allso revs to 6,000 like right now i cant belive how well it runs with a 34 pict carb its mind blowing it is so smoth running i think all my porting work payed off big time and i just love that V 26 engle cam it kicks as now this motor is not as fast as a dual weber carb motor would be but its a real friendy street motor just wanted you to know how much i like it i cant waqit to take it to the drag strip in 25 days . i think this motor is going to surprize a lot of vw guys on how well it runs at the drag strip i have a bocar carb i am going to set up for 32mm venturi i am hooked on the 34 pict carbs . thanks for al the help spencerfvee

[yellow73kubel]

The more creative part of me loves this stuff.. Great to hear some success stories. I'm very tempted to try it out this summer.

I spent a while last year doing flow simulations on 34 pict venturi designs in Autodesk if anyone is interested in the data. I found that it's a very delicate balance. The volume increase is significant in all cases, but the majority will slow down the intake velocity far more than desired. In short, a boost venturi is really handy once you punch out the stock venturi past a certain point (~28-30mm). Unfortunately, the "best" design would put it right where the choke butterfly is, so that needs a more elegant solution...

I didn't even know where to start with getting the proper amount of fuel in there, but it looks like most of you are way ahead on that.