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Sun Jul 27, 2003 8:06 pm

I have a 1641 dual port engine with a 110 cam. I am running a 34PICT-3 carb and I can't keep the engine running unless I hold the choke closed. then it runs. I have set the points and the timing statically to the proper specs, as well as setting the carb by the directions in my manual and the engine will not run unless the choke is closed. This a newly rebuilt turn key engine. I'm at a loss as to what the problem is, any help and or suggestions would be greatly appreciated. Thanks Doug

Mon Jul 28, 2003 4:33 am

Not being an expert on VWs, I have had a number of carbed cars in the past, including POS Stomberg, SUs, and Zeniths....so lots of tuning and rebuilding. Sounds like your carb is set up way too lean. Lean mixture.....needs less air to work properly....choke closed...works fine. Richer mixture....choke open...works fine. Make sure idle mix screw is adjusted properly. If that doesn't work...bigger idle jet. The same philosophy can be used for main jet. Like I said...not an expert, but it sounds logical to me.
Don

Mon Jul 28, 2003 6:23 am

hello doug, i thought you need a set of dual carb cos' you install a long duration cam. maybe 110 is mild and drivable but not suit for single carb.
if you install weber, very smooth idle and more power.
kiichiro

Mon Jul 28, 2003 7:09 am

If the car only runs with the choke on then it's to lean. Carb Jetting or more likely an air leak. How to check for Air Leaks See -> http://www.1800vw.bizhosting.com/wontidle.htm

Mon Jul 28, 2003 10:00 am

If not an obvious vacume leak like Vic suggests, the it could be as simple as a blocked idle pilot jet or a bad/loose electromagnectic idle solenoid.

see this link for more info, read down past the first three posts...

http://www.thesamba.com/vw/forums/super/forum.php?screen=msg&mid=3631

Mon Jul 28, 2003 2:45 pm

hi agian, I sure appreciate your replys. In my original post I forgot to mention that i also checked the valves and made sure they were adjusted to .006". When I adjusted the carb I found the choke idle speed screw was turned all the way in, my manual says to turn it in until it just touches and then another quarter turn. The builder assured me that the 34PICT-3 would be a good choice for this engine combination. I'll check the information on checking for air leaks and the other links to see if I can figure this out. Is there a link I can go to for changing out jets if needed? I would like to use this carb if possible, if not then i would consider the webers. At this point it seems like two carbs, means twice the trouble. Thanks Doug

Mon Jul 28, 2003 3:54 pm

DOUGSILLS, THE 34PICT-3 IS A HARD CARB TO GET TO WORK WITH THE ENGLE CAM. YOU MAY HAVE TO FIND A BIGGER IDLE JET. ITS UNDER THE CHOKE HOUSING. ALSO IF YOU LOOK AT THE CHOKE SIDE OF THE CARB, YOU WILL SE A SMALL SLOTTED BRAS PLUG. BEHIND THAT PLUG THERE IS ANOTHER IDLE CIRCUIT JET. THAT ONE ALSO SHOULD BE ENLARGED. MAYBE YOU HAVE A FRIEND WITH SOME JET REAMERS THAT CAN HELP YOU. ADJUST YOUR ACCEL. PUMP SO THAT IT SQUIRTS WITH ANY MOVEMENT OF THE THROTTLE. THE ACCEL. PUMP SQUIRTER SHOULD POINT AT THE VERY EDGE OF THE THROTTLE BUTTERFLY. THESE CARBS ARE KIND OF TRICKY, BUT CN BE WORKED OVER JUST FINE. HAVE FUN. STEVE

Mon Jul 28, 2003 5:28 pm

hey steve, how does one tell what size of jets they have, and how large should I go with enlarging them?

Tue Jul 29, 2003 10:49 am

DOUGSILLS, THERE IS A NUMBER ON THE JET. 050,045,055, ETC. ALL YOU CAN DO IS GO A LITTLE BIT OVER SAY FROM 050 TO 055. THEN RUN THE ENGINE AND SEE HOW IT RESPONDS, TO MIXTURE ADJUSTMENTS ETC. YOU SHOULD BE ABLE TO SLOWLY ACCEL. THE ENGINE FROM IDLE TO 3500 RPM WITHOUT ANY FLAT SPOTS. IF THERE IS A STUMBLE OFF IDLE TO TRANSITION, THE IDLE JET NEEDS TO BE ENLARGED. THEY ONLY WAY TO JET THE MAINS IS TO HOT LAP IT. FLY DOWN YOUR STREET, SHUT OFF ENGINE COAST INTO YOUR DRIVE, AND CHECK TO SEE THE COLOR OF #3 PLUG. RICH OR LEAN. JET FROM THERE. I'VE NEVER DONE IT ANY OTHER WAY. YOU CAN TAKE THE MECHANIC OUT OF THE BACKYARD....... STEVE

Tue Jul 29, 2003 6:30 pm

Thanks Steve, I think this weekend if I have time (helping daughter move) I'm going to check for vacuum leaks and check the idle solenoid. If that at least keeps it running, i'll pull the carb and see what number jet I have. Thanks you guys for all your help, I was really getting discouraged I got this new dune buggy and can't even drive it. Can't get any help form the Co. who built it because they went bankrupt.

Tue Jul 29, 2003 7:12 pm

you do not have to pull the carb to get to the external pilot jet, but it would be good if your going to take out the tiny one behind the small brass plug that Steve referred to and drill it out a bit. do it over a nice clean safe area, as your not likely to be like us with tons of spare shit and if you drop it your screwed!

" ALSO IF YOU LOOK AT THE CHOKE SIDE OF THE CARB, YOU WILL SE A SMALL SLOTTED BRAS PLUG. BEHIND THAT PLUG THERE IS ANOTHER IDLE CIRCUIT JET. THAT ONE ALSO SHOULD BE ENLARGED."

also, the main jet should be (IMO) bummped up from 127.5 to at least 132...