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MG Midget and Sprite Technical - Weber set-up

I would appreciate a view about the following jet set up for a DCOE45 running on a 1330cc slightly tuned engine. No idea which cam - maybe a 731.

Air bleed and idle jet F9 60
Emulsion F2
Mainjet 155
Air corrector 100 (!)
Venturi 38

From looking at general recomendations the idle is a bit on the large size (45 "normal") and the air corrector should be around 180/200. What would be the running effect of these two questionable settings?

I know it is best setup on a rolling road but currently it's in a cardboard box, having been removed form the car.
G Williams

Your venturi looks way too big and air corrector as you say looks way out. My reference book suggests the following as a start point:
Main venturi 34
Aux venturi 3.5
Main jet 130 to 150
Emulsion F2
Air corrector 175
Idle jet 50F9 or 55F8
Acc pump jet 50
Hope this helps.

On another note I notice my name appears to have become corrrupted. Anyone know how to correct it as everything appears OK in my details?

Trev
jwrydadp

Trev

You could try changing your name to something else, then change it back. It may work.
Dave O'Neill2

With the large choke at 38 mm it is harder to get a signal to the jets to feed fuel so they have to be bigger. 38 is competition size. You need to get it on a rolling road to set it up properly.

Peter
Peter Burgess Tuning

The history here is that I bought the car with the weber fitted. It was "fussy" below 2500 but above went like stink. And such a glorious noise!
At low speed as long as I didn't floor the throttle it behaved fine but over heavey right foot caused it to kick back in the drive chain and feel as though it was running on 3 cylinders.
I decided enough was enough so rather that getting involved with rolling roads and complex setting up I would replace the weber with an HIF44. That's my task over this bank holiday.
Thinking that I would sell the weber, I thought it useful to check the "settings" and that is when I discovered that, compared to advice on a few downloads I found, one or two of the settings were totally out of line with the norm. I was wondering whether either the idle jet or the air corrector (that one seems a long way out!) could have been the cause of the bottom end trouble.
G Williams

The bottom end trouble is the large choke making it require big idle and big main jet to fuel, small air corrector to try and keep fuelling at high rpm. Weber side drafts are always poor below 2500 rpm, the nature of the beast, the bonus is when you give it welly at higher rpms.

Peter
Peter Burgess Tuning

I ran a '45 with 38 chokes on our 1380 for a while , and they were too big for than as well. Nothing at all under 2000rpm, but at higher revs went very well.

On a back-to-back rolling road comparison between the HIF6/44 and Weber DCOE45, the Weber produced 4 bhp more, at similar revs, but not at all nice to drive in everyday conditions. Also the engine leaked at bit of oil as there was no proper crankcase breather system.

At a short while I got fed up with it and went back to the HIF44.

Richard
Richard Wale

Hi Richard
Fastparts at Croydon. I recall you swopping carbs between sessions on that 'Shootout'. I dont think Fastparts are there any more.
Alan
Alan Anstead

Hi Alan,

Yes it was Paul at Fastparts - good fun day that was.

The Weber result later turned out to be flattering as the HIF had a MG Metro air cleaner fitted at the time, with K & N Filter, and that proved to be a restriction in a later rolling road session - now run with a K & N large pancake filter + stub stack and get a few more hp than the Weber, but also a different cam and no back-to-back comparison this time.

Richard
Richard Wale

You'll find it very difficult and expensive trying to set it up yourself. either take it to a reputable tuner or as already mentioned swap for a HIF44, much esier to play with.
HALL JOHN

John: my conclusion exactly. I think the weber would suit those more "pioneering" souls who like to try kit which is less mainstream. It certainly looks impressive and sounds superb and I know there are contributors here who would swear by their Webers. I have now fitted an HIF44 and am currently trying to sort out a satisfactory distributor set-up. Anyone want to buy a Weber, manifold and K&N filter?
G Williams

Must say that tuning a weber or delorto isn't that mutch more difficult than trying to profile an SU needle.
The only point is you need more parts
Onno K

This thread was discussed between 20/04/2014 and 27/04/2014

MG Midget and Sprite Technical index

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