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MG MGA - A few carburettor (carburetor) queries?

The choke linkages on my carburetters have been worn for sometime so I thought I would give the carbies an overhaul before I head off to colder climes next year. (3 brg 1800 engine with a mild cam grind - H4 carbies).

First up I had to fix a broken overflow pipe on the front float bowl - I found the brass float was about a 1/4 full of fuel (still floating) - dropped it into water and slowly heated (as per the mgaguru's site) and found a minute crack around where the centre tube is soldered in - drained and re-soldered. Thought I would check float heights and both were +1/2" - I thought that is odd so reset to 7/16" and the reassembled - car started a bit reluctantly (as usual) but was fine when warmed up (more on this later).

Then removed the carbies and manifold as one to start on the linkages. All the pins and holes in the brass levers are well worn except for the 2 holes that should be sloppy - these had been bushed back to the pin size using epoxy and a brass bush! - see photo attached. This is the second A I have had to replace levers on - they must shake around a bit during driving?

There are signs of minor leaks around the jets so have removed these assemblies and will look to source teflon O rings in Oz rather than use the cork seals (anyone know suppliers Downunder?)

While I was removing the jets I noticed that the float bowls are solidly mounted, only a fibre washer (see photo) - I assume this is a PO modification as I couldn't see any mention in the company literature - I will revert to the rubber (viton) mounting system - this explains why the float levels were so low (compensation for the rubber mount thickness)!

I also checked the needles and found they are MME. These don't show up in any of the needles recommended for MGAs - does anyone else use them? They are richer through the range when compared to the 6, AO or RO needles recommended for an MGA using the comparison site?
Does anyone have the reference heights (SU Reference Catalogue) for checking what springs are fitted to my carbies (load at a specific height compressed height using a kitchen balance)?

Another query I have is that the inlet tracts look longer on my carbies to that shown in Clausager page 65 for H4 carbies - mine measure 1 7/8" from the suction chamber to the front flange - is this standard? (another pic attached.

Mike Ellsmore

Solid fixing of the fuel bowl photo

Mike Ellsmore

Long inlet tract on carby photo

Mike Ellsmore

Mike, for what it's worth, I have had no trouble with the cork seals leaking with the fuel we have here, and they have done 17,000 miles so far. Will go and measure my carbs later.
Lindsay Sampford

Brrrrrr, minus 6 here Mike! Just measured the carb inlet tract and it is the same as yours, 1 7/8".
My carbs had fibre washers on the float bowls when I first got the car, but that was obviously a bodge. I fitted the correct 'rubber' seals from SU, and they too don't leak.
Lindsay Sampford


There are two types of fixture for the float bowls and I think yours are meant to be like that (no rubber mounts).

Your choke linkages don't look bad to me - they are not doing anything when running so don't worry about them.

I would go back to the recommended rich needles for the 1800.

Good that you were able to fix your float.

M Wellard

Mike,seems fibre washers are a legitimate way of fixing the float bowls. See here:
I think the rubber alternative is meant to insulate the float bowls from the engine vibration to reduce frothing of the fuel.
Lindsay Sampford

This thread was discussed on 30/12/2014

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