MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - WEBER DGEV REBUILD KIT PARTS

My 79 MGB is equipped with a Weber DGEV carburetor. The idle has not been consistent for some time, but I never worried it.

Monday driving home from work the idle really started to drop off at traffic lights. As I drove on in 4th gear around 40-50 MPH, the car began to stumble. The tach did not respond to the stumble, so I suspected carburetor. Put the car up.

Wednesday, when I got home from work, I got the car started, but it would not hold any idle. Changed out the fuel filter, cut it open to see what crud existed; usual dirt.

Got the car to run, then drove around the area. Once the engine warmed up, I accelerated through the 1st through 3rd. In 3rd, as I floored it, the car sped up until the 2nd venturi opened. Then the car nose dived in a sputter, until I eased off the pedal. Repeated the process a few times with the same results. After returning home, I now have a reasonable idle.

I've had this car 15 years and never did any carburetor work, except an occasional carb cleaner spray and set the idle to +-1000 RPM. That said, it's time to rebuild this unit.

I have seen several different rebuild kits available on line. Checked out a few You-Tube vids. There seems to be a few different kits with varying quantities and number of components. There is also a small filter at the fuel inlet. I suppose is a separate item.

Question is which is the best kit and/or additional items to buy?

Thanx In Advance

Gary
79 MGB
gary hansen

Gary
Main thing is to get a kit that has the diaphrams in it
These perish and give problems,especially if your carb has the little triangle shaped vent diaphram
When these leak they let extra fuel in at idle and you can actually screw the mixture screw right in and they will still run on this stray fuel
Also make sure you have the diaphrams off the carb if you are blowing things out with a air hose or they will be damaged
Keep all your primary and secondry jets etc seperate when you pull it apart so they don't get mixed up
Does your carb have an electric idle fuel cutoff solenoid--If it has you need to check it has a good constant power supply with the ignition turned on and that the solenoid clicks when you connect/disconnect the power supply
willy
William Revit

Willy, thanks for your response. Just got back from a week's holiday. Ordered a RedLine kit w/accelerator pump. Also, the fuel filter and a manifold gasket.

Cheers

Gary
79 MGB
gary hansen

Rebuilt the Weber DGEV today. Much dirt,two cans of carburetor cleaner. Now good smooth idle, starts very quickly.

Still a slight hesitation and stumble when floored. All in all the car runs very well. Previously, the car nose dived and stumbled huge when the secondary venturi opened.

Any suggestions as why the secondary does not pull as it should.

Cheers,

Gary
79 MGB
gary hansen

Gary
Could be acc. pump related or might be a bit lean on the secondary main jet
What happens when you jump on the throttle quickly but limit your foot travel to half way- does it take that ok
If it takes that but only faulters when you do the same but your foot goes right to the floor it probably needs to go up a size on the secondry main jet
I don't suppose you wrote the sizes down when it was apart-???

These little webers are good little carbs but are rarely jetted for purpouse when sold new- It's more of a one size fits all but it doesn't sort of thing

willy
William Revit

Willy, you are right, I did not write the jet sizes down. It's true, when I accelerate, half way then go to full throttle it works fine; but a full throttle from idle bogs then accelerates.

Prior to the rebuild, a full throttle at any position made the car nose dive.

If it is a jet size issue, I can live with it as I don't run the car hard.

Cheers

Gary
79 MGB
gary hansen

stretching the memory here a bit but I think they came new with a 140 primary main jet and a 145 secondry main
They work well with 155 primary 150 secondry on a B
willy
William Revit

Willy, thank you for the info. As I never encountered a Weber carburetor, I am totally ignorant of the jet settings in the Weber DGEV, it gives me some ideas of what can be done with this.

Now, the jets are found on the bottom of the fuel bowl, or are they the inner tubular shaped pieces inside the vertical chambers, or are they the upper parts screwed into the vertical chambers?

Cheers

Gary
79 MGB
gary hansen

Bottom of the float bowl
The sizes are equal to millimetres
140= 1.4mm
150= 1.5mm
they go up in 5s--140 145 150 155 etc
Jets are readily available, you should be able to get them from where you got your rebuild kit

Not really recomended but--IF you can't get them you could very carefully drill them with a 1.5mm drill- best done by holding the drill bit in a vice and spinning the jet in the drill, but go slow and straight--If you go this way do yourself a favor and file the stamped in size off the top of the jet to save confusion

cheers
willy
William Revit

Thanks willy. I found an exploded view of the carburetor and it shows main jets in the bottom of the bowl and air corrective jets on the top of the emulsion chamber. This is what gave me confusion.

Cheers

Gary
79 MGB
gary hansen

This thread was discussed between 17/02/2017 and 10/03/2017

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now