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MG Midget and Sprite Technical - Twin SU linkages and LCBs

Next oddity - having got fuel to the front of the car I started refitting the carbs and noticed that the throttle linkage doesn't seem to open fully.

Car is currently running twin HS2s which replaced 45 and then 40 DCOEs I acquired it with in the interests of tractability. I bought them s/hand, again some years ago, as being from an MG and recall bolting them on without too much thought, but looking at the linkage now I can see that:

1) The lever where the throttle cable attachs has been cut and filed to avoid fouling on the centre branch of the manifold (LCB type, Maniflow I think)

2) Even with this arrangement, the cable pull looks like it will only give 3/4 or 7/8 opening at the butterflies.

The heatshield is the split type, with part attached to each carb and a bottom rail for the return springs and the cable pull looks like a nasty bit of bent metal.

So how is it supposed to be?

AdrianR

There are some LCB manifolds that do interfere with the throttle linkage, but I didn't think Maniflow was one of them.

I think we need some photos.
Dave O'Neill 2

Mine has a Maniflow LCB with the original twin 1 1/4" SUs and heat shield. There is no binding. Can take a photo tomorrow if it helps?
Jeremy MkIII

Photo would be good, although probably tricky to get a clear one - internet has many pictures that don't quite show what I want to see!

Here are my carbs.


AdrianR

It looks like a mini heatshield. The midget one is a one piece pressing and the return springs go in holes along the bottom edge. I wonder if you have the correct carb spacers. They are thicker than the mini. Midget ones are approx 1" thick where the mini ones are 3/4. It means the carbs sit further away from the manifold and the cable run is more gentle.
Bob Beaumont

If you have a Mini manifold, the carbs will sit at the wrong angle.

Of course, the heat shield could have chopped up to clear the LCB.
Dave O'Neill 2

Hi,
I took a load of photos for my blog to remember how to rebuild them. Some might help you.
http://1965mgmidgetrestoration.blogspot.co.uk/2012/12/carb-clean-up.html
James
James Paul

Adrian,

Looking at your picture it looks like you don't have the spacers that Bob mentions. That may be the reason that your linkage was modified and since the carbs are closer to the manifold, therefore lower, they fit under the bonnet.
Martin

I have spacers, but they are only 1/2". The manifold casting has 12G299 VAF cast into it, then 594 stamped above.

One carb tag is present and reads AUD325F, which seems wrong as according to the internet that should be an HS4. I have another loose tag AUD136F which is a bit more plausible*

*I owned an MGB GT once, so my box of carb bits contains a muddle of HS4, HS2 and Weber leftovers.

@James, that's yet another cable attachement variant I hadn't seen. How many different attempts did they have at this?

AdrianR

Having had another look at the photo, It may not be a midget manifold. The take off is at an angle whereas the midget one is vertical. The midget heatshield also incorporates the accelerator cable stop wheras yours appears to have a bracket. As Dave has mentioned the midget manifold has a gentler intake angle. The mini one is steeper so the carbs clear the rear bulkhead. whilst both fit the A series, the mini manifold if correctly assembled with the correct spacers etc will mean the carb tops hit the bonnet.

Bob Beaumont

Put the DCOE back on and enjoy the noise! :-D

(Those that say they aren't tractable are just doing them wrong. There is a lot of misinformation and myth out there!)

Hope you get things solved one way or another.

Malc.
Malcolm Le Chevalier

I think this photo is of standard fitment carb wise.


Nigel Atkins

After posting the previous photo I noticed the recess shaping in the middle of the heatshield that I don't think I've ever noticed before so I looked under the bonnet of mine to check and there it was so this might be a better photo for you.

In this photo the heatsheild looks to be stainless steel originals weren't) -

ETA: I wouldn't trust braided fuel hose nowadays as you can't see if the rubber starts to crack underneath.


Nigel Atkins

Adrian,
the manifold and accelerator cable link arm (it's not triangle?) at least look different to mine and the spacers on mine are 1" as best I can measure and see.

What exactly do you want a photo to show?
Nigel Atkins

Adrian,

a couple of photos of the carbs, their tags, the inlet manifold with some of the linkage and the heat shield. They all sit atop a Maniflow LCB which fitted easily.


Jeremy MkIII

Manifold.


Jeremy MkIII

Linkage - ish from underneath:)


Jeremy MkIII

Linkage from above (part). (Needs a clean).
Sorry can't get more for you without taking air cleaners off.

It's all original as it's been owned from 5 years old by my wife (she as given it to me to play with).


Jeremy MkIII

If this is a mini manifold it will be 20 degrees off from the midget and will throw the floats way off and the engine wont run

Prop
1 Paper

Thanks guys. The engine ran quite happily with this setup, so I'm going to just try and put it back together as was for now and see if it still does.

Longer term it looks like I should hunt for a proper MG inlet manifold with some spacers and then buy a nice shiny stainless heatshield (Ashley Hinton type) and see if it all fits round my LCB.
AdrianR

This thread was discussed between 27/06/2017 and 29/06/2017

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.