Weber 34 ict and their set up

[Dean]

I have fitted twin 34 icts on my 1600 sp. I changed the idle & main jets and fitted the carbs after careful balancing. The carbs are correctly installed now and the bars etc are adjusted spot on.

I drove it for the mot last week and it's not right. The timing is spot on the plugs are fine but it's flat. It just seems to lack power. I can get 55 downhill with the wind pushing the van. It doesn't overheat, backfire or anything else visibly noticable.

I spoke to eurocarb today about upgrading other jets in the carb but they said it was probably more likel to be over fuelling killing the spark at high revs and at idle causing it to run faster than it should.

I've heard/read about the standard fuel pump(which i have) delivering too much psi in the fuel pressure dept and a regulator is needed.

So can people with/without fuel regulators help me out here and try to sort this problem out?

Dean

 

[K@rlos]

i've got Weber 40 IDF's with a standard pump and a reg at 3.5psi and it runs great.

 

[sparkywig]

Hello Dean, I've had the same trouble and got really pissed off with the carbs until I got put in touch with an old time carburettor man.
The 34 ICT was developed for single use on a Bedford CF van, and all the carbs supplied are jetted for this, not for a VW.
The jets as supplied are;
idle jet 52
main jet 130
air corrector jet 160
emulsion tube F78
needle valve 175

The problem is with the fuel pressure pushing too much fuel through the large needle valve (bearing in mind that type 3's and 4's have 120 needle valves) and that the emulsion tubes allow too much fuel through just off idle.
His recommended jetting for a stock 1600 single/twin port are;
idle jet 55
main jet 150
air corrector jet 170
emulsion tubes F3/F6
needle valve 125-140

F3/F6 emulsion tubes have no drilling high up on the tube allowing the idle jet to do its job without adding early fuel from the main jet (he also said that if I solder up the top holes in the F78 emulsion tubes that will stop the off idle fuelling and then the 55 idle jets will be correct).

I've fitted the 55 idles, 150 mains, 170 air correctors and F6 emulsion tubes, but kept the 175 needle valves and fitted a fuel pressure regulator to keep the fuel pressure to 3.5psi, as the stock pump can push out up to 8 psi.
Mine is running fine now.

 

[Dean]

Thanks SW

I'm told the F6 & F3 tubes are not available so i'll solder the top of the existing ones and the smallest needle valves available are 150.

I think i'll order the reg fit and see where i go from there.

Thanks

Dean

 

[Pete B]

Have been thinking about the 34 ict setup. Do eurocarb and other supliers inform the customer that jet changes are required for install on a VW? If so, do they offer the appropriate parts FOC? If not, then that is pretty poor considering they advertise the kits specifically for 'our' engines. Obviously with ported heads, bigger valves, alternative cam etc, jetting is most likely to need fettling, but for a standard engine it should be right when advertised and sold as a kit for that application. Or am I completely wrong and they make it very clear that it is nowhere near correct, 'go sort it yourself' ?

 

[sparkywig]

Have been thinking about the 34 ict setup. Do eurocarb and other supliers inform the customer that jet changes are required for install on a VW? If so, do they offer the appropriate parts FOC? If not, then that is pretty poor considering they advertise the kits specifically for 'our' engines. Obviously with ported heads, bigger valves, alternative cam etc, jetting is most likely to need fettling, but for a standard engine it should be right when advertised and sold as a kit for that application. Or am I completely wrong and they make it very clear that it is nowhere near correct, 'go sort it yourself' ?

Pete, no, no, and no.

Thanks SW

I'm told the F6 & F3 tubes are not available so i'll solder the top of the existing ones and the smallest needle valves available are 150.

I think i'll order the reg fit and see where i go from there.

Thanks

Dean

Dean, I bought the F6 emulsion tubes and other jets from Eurocarb back in January, so they should be available. :?

 

[Dean]

SW the emulsion tubes are not available one was discontinued ( i think) the other is just not available at present.

I have however re adjusted the fuel mixture as i was running to lean and it seems to have sorted the problem, even the erratic idling has gone now when warm. I'm loving the "perkiness" of the van now :mrgreen:

 

[Pete B]

Dean, just to clarify, have you changed any components at all on/in the carbs? Are they jetted as supplied and now with a bit more twiddling run fine?
Cheers.

 

[Dean]

well i spoke too soon. :roll:

It's running really well except for a bit of popping when rolling, not accelerating, for example down a hill.

PETE

I only changed the main jet and the idle jet. I did call eurocarb for the other jets that have been recomended but two were unavailable and the others were not advised until overfuelling was ruled out. I've now ruled out overfuelling so i'll be keeping it as is unless the popping i now have is a problem cured by further upgrades.

I am happy with considerable improvement over stock carb.

 

[sparkywig]

well i spoke too soon. :roll:

It's running really well except for a bit of popping when rolling, not accelerating, for example down a hill.

PETE

I only changed the main jet and the idle jet. I did call eurocarb for the other jets that have been recomended but two were unavailable and the others were not advised until overfuelling was ruled out. I've now ruled out overfuelling so i'll be keeping it as is unless the popping i now have is a problem cured by further upgrades.

I am happy with considerable improvement over stock carb.

Hello Dean, that's probably the emulsion tubes allowing too much fuel through just off idle.
Who did you speak to at Eurocarb? The salesman or the technical bloke?

 

[Dean]

SW

I'm not sure who i spoke to but it's someone i haven't spoke to before, even though i've only called them a couple of times.

Do you know which and how many of the holes on the F78 emulsion tubes need to be soldered?

 

[sparkywig]

Just the top ones I think. It'll become apparent which ones need doing when you strip them out. There's quite a lot of holes compared to an F6

 

[Pete B]

I really hope you get this sorted guys, so there is a recognised set up for when I put these carbs on my engine!!!
I still find it absolutely outragous that the kit can be sold as being for a 1600 VW when it patently is not suitable. The fact that it fits does not mean it works. Am finding it hard to accept that the suppliers have not been brought to task before if the product is so far off the mark.

 

[sparkywig]

I've fitted the 55 idles, 150 mains, 170 air correctors and F6 emulsion tubes, but kept the 175 needle valves and fitted a fuel pressure regulator to keep the fuel pressure to 3.5psi, as the stock pump can push out up to 8 psi.
Mine is running fine now.

Pete, after much trial and error this is what I've got fitted.
Bus runs fine, and had an indicated 80mph up today on the way back up the motorway.

 

[privatejobs]

hi sparky did you fit a air balance pipe between the manifolds ta

 

[bananacustard]

I've had a pair of 34s on my bus for years now. From Eurocarb, who jetted them for my engine (1641). They've been fine, the only problem I had was over fuelling from the stock pump which eventually wore the needle valves and kept flooding the sump. Electric pump,pressure regulator and new valves and all is well again.

 

[Andy_sheff]

I'm currently having issues. The problem I have is up the revs, ticks over fine, low revs is ok, but as soon as you get your foot down it hesitates badly, and really struggles on a hill. I've done the plugs, timing, leads, tweaked the mixture screw, I suspect too much fuel as it's drinking it and there is some black on the back bumper.
Think I should take the carbs off and see what jets are in there and change them got the above??
Would be nice to get a good conclusion to this as t seems to be a common prob! If the jetting is correct, should the standard fuel supply be ok?

 

[Andy_sheff]

Also, any diagrams of which needle is which

 

[Andy_sheff]

Took one of my carbs off at the weekend to check jets, and yes thy are the wrong ones, made an order last night from eurocarb, all except the needle jet, came to about 50 quid for them all x2 and a few gaskets, fingers crossed.

 

[user 20733]

As mentioned before, the stock pump is too much for carbs. You need to drop the pressure to below 3.5psi before you can do any kind of tuning/diagnostics. I have one of these and mine runs fine.

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