UPDATE: What do you think of these carbs?

[Baldrick]

Hi all

I'm getting increasingly hacked off with the twin carbs on my new engine. The carbs are a bit of a "home brew" from the engine builder and although they are original webbers they are not common on VWs. They have also been the source of most of my engine problems over the last year.

The problem as I see it is:
1) Fuel consumption - I only get between 16 and 22 mpg.
2) The inlet manifold makes it difficult to get to the spark plugs at the front and impossible to get to the plugs at the back. I don't want to have to pay someone to do something like change the plugs by taking the engine apart first.

I'm thinking of biting the bullet and just changing them in the hope that I can cure or improve the above problems. However, I'm not technical and don't really understand the differences between the available carbs.

I can read about 34s, 40s, 44s etc... but what does this all mean? Is there anywhere that will explain what each does and the benefits?

Thanks

 

[sweat69]

Hi buddy show us some pics of the carbs so we can see what you have got.
Also what is the spec of your engine :?:

 

[Baldrick]

Add to the above issues that they weep petrol!! They have done this from new but I thought it was fixed. I'm not sure if the problem is from the 100 miles I drove yesterday or the fact that I've just filled up, but the gaskets seem to be porous and let petrol seep out.

Anyways, the engine is a 1776. The carbs are weber 36 DCNV with 28mm chokes and the cam is stock.

Pictures:

Thanks

 

[dubs and classics]

I will confess I am not too familiar with dcnv's, but if the gaskets are wet with petrol then they are obviously flooding which would account for the high consumption. I would suspect that you need a pressure regulator if you dont have one. Im sure someone with experience of these carbs will be along shortly to tell you what pressure they like.

Personally I like dellorto drla's or weber drla's on aircooleds, but it would be fairly costly to change as you would need the manifolds and linkages etc as well. Probably in the region of £500 ish all in. More if you are going to pay someone else to fit them..

 

[Geeze]

Blimey, DCNVs not seen a set in a while.
They're basically DCNFs from memory (later variation?), usually seen on type 3s (fast/square/notchback, not wedge) because the low height helps get them under the lid (hence the stumpy manifolds).

Have had them way back on a type 3 and they were actually pretty good on fuel in that so suspect the advice to check the fuel pressure is the best (and cheapest !) place to start. You're running a stock pump, so check the pressure and shim it up with gaskets as required. As with most webers, they don't like much over 3psi....

 

[Baldrick]

...it would be fairly costly to change as you would need the manifolds and linkages etc as well. Probably in the region of £500 ish all in. More if you are going to pay someone else to fit them..

I know .

I just want to cut my losses and get something that will work properly. I really want to know what my options are and what I can expect from the various "standard" carbs.

What are the differences between 34s and 40s or anything else that is commonly used?

 

[six]

use suspects are

dual weber ict34 nice simple carb, easy to maintain. doesnt at lots in terms of performance but are fairly frugal on fuel as a result. they are the cheapest option

weber idf 40 / dellorto drla 36

nice carb imo of a bus, keeps the torques up in the ranges normal busses run in, run out of puff at the end of the rpm range. about 500 all in for carbs manifolds linkage good on fuel. Very granula in terms of adjustments, can change the vents and all the jets, so you can get it spot on for application

weber idf 44 / dellorto 40

same as above, are very flexible too. great if you have big valve heads and want to run above stock rpm range.


thats just what experieces i've had, im sure there is plenty of debate etc. obviously best thing i woudl suggest is have a chat to dellorto.co.uk and let them know what you got and they can recommend options.

 

[dubs and classics]

If you are dead set on getting rid of your setup but still want twins then probably the cheapest option is the ICT's as suggested by six. Great little carbs really, not much to go wrong with them and fairly cheap to setup.

I think I would be tempted to spend a bit of time getting your existing setup right first though. You may find that once its right it will give a decent mpg and performance. As for the plug access problem, maybe there are taller manifolds available? I would talk to Eurocarb and see what the options are for your carbs.

 

[petegee56]

If you continue to run twin carbs you will always have the problem of getting to the plugs, Its a real pain in the ass but once you learn the technique of doing it you soon get the hang of it, you need a socket extension, a socket fitment with the rotating end and then its a case of cramming as much of yourself into the engine bay as possible.

cant really help with your other issues as changing spark plugs is the limit of my knowledge, would it be worth a rolling road session, they could be jetted all wrong hence the large fuel consumption.

Pete

 

[mjknight71]

twin kadrons...not fashionable...but functional....best value twin carbs according to one of them magazine things you can read for free in WH Smiths whilst waiting for the other half

 

[Baldrick]

Thanks for the comments guys, it is all appreciated but to be honest I just don't know what to do.

I'm well pi$$ed off this morning as I have petrol now dripping from one of the carbs. I'm guessing this is because I've just filled up and there is some sort of pressure forcing petrol into the carbs.

I've already spent a fortune on the engine and I just don't know what the best thing to do is. The carbs have just never been right and I've pretty much lost confidence in them.

 

[Geeze]

Where's the fuel leaking from? It could well be a sign that they're being fed too much pressure (it fills up the carb, then slowly finds it's way out while it's parked).

Think that the cheapest option would still be to start there.
For the manifolds, Gene Berg used to do a taller set for DCNFs which should fit DCNVs although as has been said, the access to the back plugs with any twin carbs set up is still an artform :lol:

Failing that,

twin kadrons...not fashionable...but functional....best value twin carbs according to one of them magazine things you can read for free in WH Smiths whilst waiting for the other half

WHS, much underrated carb. The linkage is truly awful but as a result you can often pick up a nearly new set for cheap from someone who couldn't get them set up. Then throw the linkage away and use a decent (eg. CSP) one and you're good.

 

[mjknight71]

I have 2 sets one on my 1600tp in the bay.....and another set on the 1776 that is going in my splitty.........

Cannot fault them...the 1600tp set cost me something like £150 to buy...new set of filters and they have been super...they were recommended as the old scholl upgrade....they have been around years and have always worked........

....... :mrgreen:

Good point about the linkage

 

[Baldrick]

Thanks again for the help and suggestions.

I'm back in conversation with the engine builder so might be able to get something sorted "out of warranty". But if not kadrons sound like an option.

Thanks again...

 

[johnandkatrina]

Having the same problems leaking fuel on my new twin ICTS, I have just bought a fuel shutoff solenoid which will close when de-energised, going to fit it in the next few days, so will let you know if it stops the static leak, might be a possible solution.

 

[mjknight71]

ebay... 200617863824

:mrgreen:

 

[petegee56]

http://www.volkszone.com/VZi/showthread.php?t=716072" onclick="window.open(this.href);return false;

Kadrons

 

[johnandkatrina]

Fitted the fuel shut off solenoid yesterday, just checked it this morning and there is no fuel seeping from the carbs, so thumbs up at the moment. very easy to fit wired it of the coil with a 3amp in line fuse, hope this helps you a bit

 

[Trikky2]

If the carbs are seeping fuel even when parked its an indication the needle valves in the top of the float chambers are not shutting off. They could simply be out of adjustment - often people leave off the washer that should be between the needle valve and the carb top, which causes the level in the float chamber to be too high.

The other possibility is that they are worn and need replacing. Sometimes gunge or bits of rubber from ageing fuel pipes can jam them so they dont close off completely, though its unlikely to be occuring on both carbs at once.

These carbs should run fine if they are in good order and correctly adjusted giving 25 to 27 mpg on a run (not in town/heavy traffic though).

 

[K@rlos]

Weber IDF's and ICT's along with Dell'orto DRLA's are tried and tested over the years and I would personally rather spend £500 on a set of them because they are proven on Aircooled engines. 'Homebrew' stuff may be a cheaper alternative to start with but will cause heart ache :?