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VW 1776 trike weber dfev stumbling badly
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Lev levvin
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Joined: June 23, 2016
Posts: 3
Location: Cornwall UK
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PostPosted: Thu Jun 23, 2016 4:24 pm    Post subject: VW 1776 trike weber dfev stumbling badly Reply with quote

Hi
First post on here but have read info for past few years
I live in Cornwall Uk and have built a vw 1776 twinport engined trike over past 2 years

I've used 90% brand new parts in engine
It's running new barrels and Pistons, huco 2.5psi electric pump, accuspark vacuum dizzy, Bosch lifetime leads and plugs, 75a alternator, filter King regulator filter and skat external spin on oil filter/pump.

I also have a brand spanking new weber 23/36 dfev single carb and fully heated manifold fitted
This is where I'm hitting problems

The engine runs smooth as silk on tickover, 950 rpm and runs like a modern car engine, no surging or vibrating at all

I've checked the combustion with a gunsons colourtune, perfect blue flame.

I'm running a 45 idle jet and mixture screw out 1 3/4 turns at best lean idle

But... As soon as the throttle is opened the engine gasps and stalls 😞
If you blip the throttle then open it normally it'll pull through and drive ok
But every gear change and pulling away from stop and it'll hesitate and stumble

The choke is fully off

This is at 950rpm onto butterfly valve starting to open

Please can someone advise on how to fix this?
I've tried weber uk but they were no real help other than sending out two different idle jets to try

the carb was supplied as a kit for vw 1600-1800 with a 60 idle jet
It won't run ok with this jet, chugging black smoke and stinking over rich
The 50 is almost there but 45 is definitely best for tickover and driving

The hesitation doesn't change on any size jets

I've built this trike so I can give my wife with MS a good summer as it's unlikely she'll be able to ride pillion next year 😞

With this problem the trike is very dangerous as it stalls pulling out of junctions

Help very much appreciated thank you
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rsfowler
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Joined: December 30, 2009
Posts: 102
Location: Bedford VA
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PostPosted: Mon Jun 27, 2016 9:46 am    Post subject: Re: VW 1776 trike weber dfev stumbling badly Reply with quote

I had the same problem on my Trike
I have a Weber 32/36

I tried a number of different things some helped a little but not completely.
A couple weeks ago I tore the carb down again, cleaned it and replaced the accelerator pump diaphragm and have not had the problem since

See the links at the bottom of my carb page

http://3fowlers.com/carb.html
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Bob
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styroman
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Joined: March 15, 2014
Posts: 131
Location: Snohomish, WA
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PostPosted: Tue Dec 06, 2016 2:29 pm    Post subject: Re: VW 1776 trike weber dfev stumbling badly Reply with quote

I tried everything with mine, rebuilt, retuned, replaced, and retimed; then installed dual carbs; problem solved.

I suspect that I have two weak cylinders on the driver's side so that they do not draw as much air at idle. This would cause a stagnation of flow, and condensing of fuel on that side. I could set things up to run fairly well at idle, but then it would choke up when applying throttle. My fix was to go to an EMPI Dual EPC 34 Carburetor Kit; and, because I now can tune the two sides separately, and there is no longer an airflow stagnation in that longer driver's side intake tube, that seems to have negated the problem. One day I will redo the rings, pistons, and cylinders.

I suspect that even with good compression on all four cylinders, the longer driver's side tube can still be a problem in open engine compartments on cold days.

That's my story and I'm sticking to it.
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Bashr52
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Location: On an island in VA
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PostPosted: Wed Dec 07, 2016 6:05 am    Post subject: Re: VW 1776 trike weber dfev stumbling badly Reply with quote

Weber Progressives are known to be a problem on VW engines. They were originally sold/provided on Pinto's and later adapted for VW's.

Check out this thread:

http://www.thesamba.com/vw/forum/viewtopic.php?t=386388&highlight=progressive
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styroman
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Location: Snohomish, WA
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PostPosted: Wed Dec 07, 2016 12:41 pm    Post subject: Re: VW 1776 trike weber dfev stumbling badly Reply with quote

Bashr52 wrote:
Weber Progressives are known to be a problem on VW engines. They were originally sold/provided on Pinto's and later adapted for VW's.

Check out this thread:

http://www.thesamba.com/vw/forum/viewtopic.php?t=386388&highlight=progressive
Very nice article.

Concurring, I started with a Weber, and replaced it with an EMPI, and had the same problems with both on my open 1776. I notice that the linked article was written in 2009. In researching the EMPI before purchasing, i read this article and many other complaints about the EMPI copy. But I also found that most people agreed that EMPI had fixed their problems with the carb, so I felt confident purchasing it. The company I purchased from shipped my EMPI progressive already setup with proper jetting for my mildly cammed 1776 at sea level, and it ran well out on the road, the same as the Weber; but still had that low end hesitancy.

I run an 009 distributor also, and knew that a properly setup vacuum advance distributor would work better with the progressive carb when I made my decision for dual EMPI ECT carbs. It runs great now, but I have not driven my buggy enough yet to decide whether to install a vacuum advance distributor, as I also launched into some other upgrades for the Winter.
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Dr OnHolliday
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PostPosted: Wed Dec 07, 2016 4:10 pm    Post subject: Re: VW 1776 trike weber dfev stumbling badly Reply with quote

Eh - my progressive weber and 009 run like a raped ape with no lag or flat spots...

I'm even going to use them with the new turbo'd (blow thru) engine I'm building. At some boost level the Weber will become too small, but to start at lower boost levels it'll do just fine...

It's all about cleanliness, correct jets and no undue wear like throttle shafts.
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1965 Type 1 sunroof Baja / about 70k miles on self-rebuilt '74 1600 and counting / SP heads and aftermarket valve keepers / non-doghouse shroud with external cooler and filter / 1.5 qt extended sump / Weber 32/36 DFAV progressive carb / 009 dist with Pertronix / 1.25 ratio rockers and ball adjusters / 1.5" stainless steel J-pipes and carbon steel baja exhaust
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styroman
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Location: Snohomish, WA
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PostPosted: Wed Dec 07, 2016 6:00 pm    Post subject: Re: VW 1776 trike weber dfev stumbling badly Reply with quote

Dr OnHolliday wrote:
Eh - my progressive weber and 009 run like a raped ape with no lag or flat spots...


I have heard that some people have good performance with that combination, but they are usually somewhere in the south. Seattle's average temperature is 52°, and Cornwall, UK is about the same.
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