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MG MGB Technical - Weber Carburator 45 DCOE Sidedraft

I just purchased a 1978 mgb roadster. The previous owner installed a Weber 45DCOE side draft Carburator with K&N filter. The car had an manual choke and when it is running warn, the engine runs at 1000-1500 RPM's. He mentioned that it is running very lean and it needs adjustments. Can thos of you in the Toronto area suggest some good machanics who have the skill to work on these cars and aren't too expensive.
Joseph

The problem I think you're facing is finding someone who can tune 45DCOE Webers, as well as someone who knows MGBs. Good luck in your search.
Derek Nicholson

There's a pretty standard set of jets that can make a weber work with any given MGB engine. If you post the expensive bits you've already got in your weber: main venturi, aux venturi and emulusion tube, someone will be able to post recommendation for the tunable bits. If you engine has a non-standard compression ratio or cam or something similar you need to mention that too.

The weber for my basically stock MGB engine came with: 33 main venturi, 4.5 aux venturi, 55F9 idle, 135 main jet on an F15 emulsion tube and a 170 air correction. It runs quite well with that combination.
Mike Polan

Are you saying that you can't adjust the idle any slower than 1000-1500? If that's the case, something in the linkage is amiss - you should be able to set the idle as low as you want. Mine likes to idle at 1000, but that's a cam issue - not a carb issue. I can set it lower, but it idles too rough. If you have a hot cam, you won't be able to get a smooth 800 RPM idle...
As for "adjustment", there really isn't any beyone the idle speed. You don't "adjust" in the conventional sense - you change to different jets, etc. The good news is that once it's set right, you can forget it - it can't really go out of tune. The bad news is that experimenting with jets, emulsion tubes, etc., can get a little expensive. You can also chase your tail forever as you swap parts trying to get it set up right.
Mike's advise is good - post as much info as possible about your engine and what's presently in your carb. Someone will be able to give you come advice...
J.G. Reed

I don't know how my 45 DCOE is set up, but it is on a stock cam and head. It idles well, starts easily, but has little power for hill climbing. I run points and stock coil, the engine compression is good in all cylinders. Does this sound like a carburetor problem, and will a 45DCOE work with a stock B set up?
Rodger

Hi Rodger - the weber should be as strong as SU's on a stock engine, though probably not as fuel efficient. The car should pull pretty well up hills.

Same as for Joseph, you need to know what's in there. The weber dcoe comes apart without taking it off the car, though it's a bit easier if you do. Remove the locking screws on the lower sides of the carb body, then pull out the aux venturi and then the main from each side (they can be a bit tight). There should be small numbers on the aux venturi (say 3.0 to 5.0), and on the front of the mains (usually 32 to 40). The mains size is the most important one. I've got a set of 33 mains and 36 mains, both sets pull very well.

Careful when you put the venturis back to ensure they're properly lined up with the lock screws and bleed screws, or you'll damage them and the car won't run right.

Your lack of power sounds like the main jets, they come from under the mickey mouse hat on the top - bottom bits of the longer pair of the 4 tubes. The colour of your plugs might help to know which way to go, but if you post what size you've got and I'm sure someone can help cheaper and easier than trial and error.

Mike Polan

Joe, [can I call you Joe?]
My son Jon, the one who went bad. he bought a Porsche 924.
Installed 2, 40mm DCOE Webers on his car. it has problems thoughout the range.
I called Paeco Ind. in Alabama, they were quite helpful. You may need a exhaust gas analyzer to get the idle right though. here's their phone # 800-326-6401
BTW I'm sticking to my twin HS4's. That's my story and I'm st....
Safety Fast
Dwight
Dwight McCullough

This thread was discussed between 14/05/2003 and 17/05/2003

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