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MG Midget and Sprite Technical - carb spring attachment

Hi

Where exactly does the middle return spring attach to on a twin 1.25 inch SU carb set-up please?

I am trying to sort out a previous owner's bodges (missing central spring, damaged and non-standard springs and bodged throttle cable connection to the butterfly and a bodged choke able attachment with an odd spring attached to the cable clamp).

The diagrams in the workshop and parts manuals are no use for the top attachment, while clearly showing the lower connection to the heat shield. The other two springs are easy to locate on the heat shield and to the carbs, but where/how does the middle spring connect to the butterfly linkage? the 'obvious' point is to a groove on the butterfly, but that would mean the spring opens the throttle. And am I correct there is no choke return spring?

Thanks
Mike
M Wood

Mine attaches to the clamp screw which holds the throttle cable. I have seen them fitted through the eye in the split pin.

Bob Beaumont

Mike, If u r a 1500.

There should be two circular springs (one on the inside face of each carb) that hold the jets up / return the jets to their preset position. These also help the return of the choke. They are a pain to put back on when they come off so it may be that the PO has put some springs on to aid choke return (jets return up) that are not on the original diagram. The throttle is simply a return spring and there should be a small tang or plate with a hole in it for the return spring to connect to on one of the exhaust downpipe bolts. The strength of this spring depends on two things. 1) how hard you want the accelerator to be to push and 2) how bad a throttle cable you have. If the throttle cable is very bindy then I suggest you replace with a kit from a motorbike supplier where the cables are Teflon coated and loverly. The ones from Venhill where a kit incliding all the bits that fit the Midge is about a 10 er are very good.

Hope this helps.

Dave
Dave Squire

Hi Mike

Just a couple of photo's that may help you.


Ian

I Pickering

And Another.

I Pickering

Mike,
(depending on how your carbs linkage is set up) the centre spring hooks into a hole in the triangle plate
Nigel Atkins

Mike,
the last three posts refer to 1275s

to save confusion you could add your vehicle profile to be viewed and/or put up a photo of what you mean which is especially helpful if things aren't standard for whatever reason

Nigel Atkins

As he has 1.25" carbs, it isn't a 1500.

Sometimes there is a hole in the triangular plate, sometimes the spring hooks over the cable clamp, as Bob said. It depends on the linkage.
Dave O'Neill2

must admit I'd forgot that

but who knows if the PO was a real bodger :)

the three of us agree that it depends on the linkage but the standard photos wouldn't show the difference even the two Ian was kind enough to put up don't show the connection and the two I have are no better

I was also trying to encourage Mike, if he wants to, to put up a Vehicle Profile and/or a photo of the area as other items might be spotted
Nigel Atkins

Hi all

Thanks for the help.

Sorry, I should have said - the car is a 948cc A Series engined MKII Sprite.

Picture attached (choke cable attachment & its spring attachment not visible or front spring). I now know the central spring goes on the throttle cable attachment at the butterfly (and will replace that screw and nut with the proper fitment).

Good tip on sourcing a replacement choke cable. No idea why it has been put into the front carb, as well as attaching a spring from the bottom of the heat shield to the screw of the choke cable connector(AU 34) bending it.

Any tips on placing a picture on my profile - can't seem to upload one (even when small enough file size) or make my vehicle profile visible.

Cheers
Mike

M Wood

I meant AEU34 for the choke cable trunnion and screw.
M Wood

Appologies, didn't realise carb size from original post.

Customise from the top menu bar does most stuff and says what to do with your car records to be viewable. Look at the last few options.
Dave Squire

or click on another poster's 'View Vehicle Profile' then go to almost the very bottom of the page and follow the instructions and hyperlinks

you might need to resize your photos but the one for your engine is literally the size of a large stamp on my monitor so not as much as that

ETA: I read the carbs as inch and a half, I'm not used to this new metric system yet
Nigel Atkins

here's another pic that will help

David Smith

This thread was discussed on 29/11/2013

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