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MG Midget and Sprite Technical - Weber DGV

I have fitted a weber DGV manual choke to my 1500. Runs fantastic once warmed up but starting is a pig! The problem is I can't find any fast idle adjustment to the carb so starting it up simply puts the idle at around 400 rpm so I have to keep my foot on the gas until it is warmed up. This cant be right surely there must be a way of adjusting the idle speed when the choke is engaged?

Before anyone asks why I have taken off the twin SU carbs as these are the best carbs for the car blah blah blah. I am rebuilding them and had this weber so thought I would see how it compares to the twin su set up.
C Carter

This doesn't specifically help, but our Spitfire loving American friends (enemies?!) seem to love putting the DGV carb on their engines. I think perhaps the DGV costs about 20 pence over there. So perhaps a hunt around on some of the american triumph forums might find you an answer.

Interested in the results as I am ditching the SUs for a DCOE.

Malcolm.
Malcolm Le Chevalier

I have been searching Malcolm but a lot of them have electric choke which does have fast idle adjustment. How is you car coming along?
C Carter

The Weber DGV does not have a separate fast idle screw. Rather, the linkage from the pivot (bell crank) that opens and closes the choke plates has a small piece of rod which goes downwards and connects with the throttle linkage. When the choke is applied (the plates close to restrict the size of the openings) this rod causes the linkage to move away from the hot idle adjustment screw, opening the throttle more and providing a higher idle when the choke is engaged. The rod linking the throttle and choke has a bend in it and it is adjusted to proper idle by bending the rod more to open the throttle more. These adjustments are best made on the bench as it is much easier to see the parts, remove the connecting rod, then bend it, then reassemble the system, then check to see that it is working. Then, you need to reinstall the carb to the car and see if the fast idle is sufficient to you needs. A cumbersome, not easily adjusted system.

The Weber DGV carbs are popular in the US in places where emissions testing takes place because the later model MGs had a single carb. My state allows me to replace the single carb, for emissions purposes, with another single carb, but not twin SUs. Hence, I have run the DGV on three different MGBs over a period of some 15 years.
Les Bengtson

Interesting info there Les. Thanks for sharing with us. Is it correct that the DGV was used on heaps of Fords etc. so are readily available in state-side scrapies?

Car is coming along OK. I am a bit at the mercy of the neighbours at the moment. In that in order to weld I run an extension cable from a nearby house. Unfortunately the person who owns the socket is away (he is retired and takes very lengthy holidays!) and has turned off the socket.

Once I get some 'lectric though I have loooooads of welding lined up to do. Hopefully with some long evenings I can get the welding finished up in the next couple of months. Then paint and rebuild over autumn/winter.

Getting married in April so it is a race to have the car ready for then!

Malcolm.
Malcolm Le Chevalier

Thank you for your input les very interesting I know the linkage you are referring to so will have a look on the bench. It's amazing how once you have explained this to me it all makes sense. fingers cossed I will soon have it starting on the button so I can get her through the mot.

I know how you feel Malcolm I have a nice big garage that I rent but no power. I stripped the whole back end rebuild rear suspension, axle and stripped the boot floor all buy hand! The welding had to be done by driving the car under the cover of darkness to my friends house to do. So frustrating but then again when is anything on a midget not frustrating.
C Carter

Malcolm

"Is it correct that the DGV was used on heaps of Fords etc. so are readily available in state-side scrapies?"

Ive seen them at the scrappers on BMWs Jeep and MGs
over the past 15 years.

Not so often these days as the drive for scrap metal has turned many of these vehicle into Tuna cans.
Newer cars are fuel injected. Im amazed to see what I consider modern cars being thrown away these days.
Saturns still seem new to me but there heading off to the parts yards in droves!

Steven Devine

Malcolm. A licensed version of the Weber DGV was produced by Holley carbs as the Holley 5200. This was used on a number of "economy" cars from all of the major US makers. It is not, however, a direct copy in that it uses five, rather than four, bolts/studs to hold the carb to the intake manifold. To the best of my knowledge, no company in the US is producing an intake manifold to adapt the Holley 5200 to any MG. The two intake manifolds that I have seen were set up with a four stud mounting surface that will only work with the Weber DGV series. I would note, however, that the humble VW "Bug" was quite common in the US back in the middle part of the last century and the Weber DGV was, and is, a common replacement carb for that car. Hence, the Weber has been well established in the US for something over fifty years and, having been produced under license, many mechanics are familiar with the system. Not something which could be said for the SU carbs, even though the SU is, in almost every way, superior to the DGV if one understands how to tune them and set them up. Having used both types over a period of decades, I would, always, opt for the SU carbs over the DGV unless there was some form of legal prohibition against doing so. (As in the requirement to only use a single carb on the 75 and later North American specification vehicles as part of the Arizona emissions requirements.) The fact that a new Weber DGV and new intake manifold sell for less than a new pair of SU carbs alone will make it more attractive to the individual on a tight budget. And, replacing an old, badly worn set of SUs with a brand new Weber might well convince many people that the Weber is an "upgrade" as many of the sellers claim. But, a better increase in power would have been noticed with a properly rebuilt or new SU carbs if one had the budget to afford them.

Les
Les Bengtson

This thread was discussed between 24/06/2013 and 25/06/2013

MG Midget and Sprite Technical index

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