Weber 38 DGAS help

[thebarbs]

Hi all,

I have a 38 DGAS fitted to the Ford Cologne/Taunus 2.3L V6 in my Cabrio, tuning the carb is proving to be difficult, any advice or solutions would be appreciated. I have already downloaded tuning instructions from various sites, so help here is not needed, just with the following.

1. Getting the engine to tickover below 1200 rpm is/was impossible, even with the idle adjustment screw turned out fully (Throttle cable is disconnected)

2. This is making it difficult to set the timing as I do not know if the mechanical advance has started to engage at this speed.

3. Adjusting mixture screws does not make any difference to the engine tickover speed or any audible change to the engine. Also the engine hesitates on rapid throttle opening.

4. I have checked the float level and adjusted to specification, the float needle and seat are both as new.

5. I have an electric fuel pump which is rated 3 to 4 psi

6. The final thing that is probably causing all my problems is - one of the venturies (only 1) is constantly dribbling fuel onto the butterfly valves, what could be causing this?

I think this is overfuelling the engine as I get loud pops from the exhaust when the engine stops.

Any help or suggestions please.

Regards

Steve

[gouldsborough7]

Re: Weber 38 DGAS help

Steve
I had this type of carb on my previous Berlinetta (built by another guy) with a 2 litre Pinto engine, and it caused me a heap of trouble. Apparently fitting this jumbo carb was considered to be a tune-up mod. Might have been OK if it had been new and tuned for the engine.

Unlike your experiences, when accelerating the car went like a rocket and usually ticked over OK but lumpy when hot. Not good in long motorway queues!

It gave all of the symptoms of running very rich, with black spark-plugs and black inside the end of exhaust pipe, and was a real SOD to start sometimes with float-chamber flooding. If it didn't get going with the 3rd turn of the key then it was plugs out and clean!

It started life having an auto-choke, which I quickly got rid of with a manual conversion. In fact, I fitted 2 choke knobs, with 1 operating the butterflies and the other controlling just the revs. This at least gave me better control on the cold-starts.

I remember there was a problem with the vacuum pipe from the distributor, which apart from having a small split I believed the bore was too big. There was an initial hesitation when pressing the accelerator pedal. I improved this (but didn't cure entirely) by replacing the pipe and fitting a proprietary brass jet in it, to reduce its bore to around 2-3mm. This softened the effect of the ignition advance/retard mechanism in the distributor. Also the mixture jets got changed with smaller ones.

Other problems which affected the running were traced to a duff HT lead, which was gradually burning out where it fitted on to the spark plug (new set fitted as a result). Also, the car came with a worn Distributor cap (contacts inside a bit burnt)with ignition timing out of tolerance. The valve clearances were not ideal, but adjustment made no real difference to the running.

Finally I bought a brand new 32/36 Weber with K&N filter designed for the engine (should have done this on Day 1), which rectified most of the real snags. In particular, it got rid of the fuel-rich symptons and made starting a lot more reliable. The mpg improved as well. I managed to sell the old carb to a guy who was in the refurbishment trade, so that helped to offset the outlay.

Hope this helps
Cheers
Mike

[dogoncrazy]

Re: Weber 38 DGAS help

Steve
I seem to remember one of the members having similair probs[possibly Bob Jackson] In his case I think it came down to an air leak caused by a missing seal between master cylinder and servo.Check for air leaks at manifold and any gas recirculating hoses etc.

[thebarbs]

Re: Weber 38 DGAS help

Hi Alan and Mike thanks for your inputs.

The carb was bought new and fitted in the UK before I came to NZ (6 years ago)and is the correct one for the engine, all ignition leads are new and all new gaskets fitted to the carb manifold, as far as I can tell (Carb cleaner spray check) there are not any air leaks.

I believe the problem lies within the carb, possibly still flooding or an internal diaphragm is split/worn.

I am going to try higher grade fuel, the 91 octane may not be up to the job!

Regards

Steve

[thebarbs]

Re: Weber 38 DGAS help

Finally got it sorted. the 91 fuel probably was not helping, but the big thing was the fuel pressure. After digging around the internet I found the 38 DGAS does not like a lot of fuel pressure (3 1/2 psi max) my electric pump peaks at 4psi. Amazingly I still had the original fuel pressure regulator from my donor car which I have never had fitted in the 8 years my Marlin has been on the road, fitting this immediately stopped the jets from constantly dribbling into the carb and tuning up became a breeze, now runs sweet.
This begs the question though, was this high fuel pressure causing problems on the original Ford carb and I did not need to buy the Weber? for the first time in 8 years my Marlin is running the best ever.

Just in time for the summer

[djj_engineer]

Re: Weber 38 DGAS help

Hi Steve
Only just read your forum.
I spent some time, 2 years, trying to get my Cabrio to run all the time.Progressivly low fuel pressure until none at all. I used bigger and bigger pumps until i renewed the tank feed and the problem disappeared.
However I now had too much fuel. The pumps were overpowering the SU's . So I fitted a Pressure King set to 2 psi and now all is happy.
good to know you have a solution.
DJ