MGB & GT Forum

I bought a 77 MGB that had been stored (inside) for more than 2 years with the intent to restore it. Before I tear it down I want to get it running and asses the engine. It was hard to get it running, but after a new alternator, and a new fuel pump, and some starter fluid, It ran very roughly but failed to idle and quickly stalled. There has been an upgrade to an electronic distributor, and the addition of a down draft Weber. I removed the cap and rotor and added 3in1 oil to the felt pad. Now it will idle but it stalls once the throttle is advanced. Any suggestions?

Thanks, Wool

it's probably leaning out on sudden acceleration.

ON SUs, easy to solve. On a Weber, not so.

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1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed

Can't help with the Weber, sorry.
Have you checked for sufficient fuel flow? Disconnect supply line at carb and put it in a jar. Ignition on and see how much fuel you get and if it has no bubbles in the flow.

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"It is a mistake to try to look too far ahead. The chain of destiny can only be grasped one link at a time."
Sir Winston Churchill
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and finally to your very soul."
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Make sure there is oil in the dash pots.

The Weber carburetor may have gummed up jets from being idle so long. Your best bet is to remove the top and clean out the float chamber. RAY

Yeah, the old take apart the carb and hose it down with Clean-R-Carb technique is what I'd try
too.

the Weber DGV "Pinto carb" has a history of lean on acceleration. See below.

Proper solution means changing parts within the carb. They are not "adjustable" like SUs but changeable as in changing one of many different little pieces within the carb. Each costs money. And knowledge.

""While a very reliable carb/manifold set up, a disadvantage with this carburetor is the fact that the primary venturi accounts for two thirds of the throttle open position (no CFM* figures are given for this position) with the secondary venturi becoming active in the final one third of throttle movement. This carburetor requires excessive initial ignition timing advance to avoid stumble on take off (if the ignition timing was retarded, we would have to open the primary throttle plate to obtain the necessary idle; this would expose the progression bleed holes which in turn would require that the idle mixture be leaned to compensate for this richer mixture condition. The end result being very little progressive richening upon further throttle opening, especially at snap throttle and so the stumble). Carburetor can be modified to allow the primary & secondary throttle plates to open simultaneously plus modifications to the progression circuit and accelerator pump. Unfortunately, the company that used to provide this service no longer offers this modification. Maybe a search on the web will turn up a company that can help you.

from mgbmga.com
http://www.mgbmga.com/tech/mgb19.htm

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1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed

Thanks everyone for your input.

Mac, I learned many years ago that Carburetor is French for "Leave IT Alone"

But unfortunately I can't ! I have to muddle through fixing this expensive upgrade that came with the car.

I've begun by taking the top half off as Ray has recommended. The choke linkage is keeping it from coming off all together. There's a teeny tiny circlip holding it in place.

Is there a rebuild kit?

Wool

Rebuild kits are available for that carburetor. I believe that the problems you are having are due to clogged jets - they will need to be carefully removed and cleaned. Often a fine wire can be pushed through the jet to clear obstruction. Most kits do come with decent diagrams and instructions. Good luck!!

Blessings

Paul

Thanks to each one of you for your insight.

I took the top half of the Weber off (without loosing that tiny circlip) The float chamber has a lot of sediment at the bottom. Mostly green stuff.
I took steel wool to everything that could be reached, than gave it a good spray of carb cleaner to rinse out any of steel wool fragment. I removed all of the jets, and pocked wire trough every orifice. Once reassembled, I fired the engine up. It ran nicely, and eventually I was able to increase the throttle with out it stumbling. The bad news is know that its running, I can hear all the rattling coming from the engine. Rebuild will be in order. Hopefully I'll get a nice New England day to drive around before I take it apart.
Thanks again to all of you. Wool

Put a can of Seafoam in the tank the next time you fill. Can't hurt, and will probably help. If you read the can, you can put it through the induction, too. I run SU's, so I don't know how to do it with a Weber.

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Jim K is a grease-stained wretch

Never tried Seafoam. Always used Techron in the BMWs

How does one distinguish which Weber Carb is on the car?

Take a picture and let us see.