Overflow on carb

[SB - Nigel]

As I'm away on a Scottish Borders tour at the weekend now my '73 Midget decides to play up!

Serviced it a bit early two weeks ago (annual 12,0000) to make sure it was ready and allow a couple of weeks just in case (previously serviced Oct '08 6,000 6 months)

Overflow (on front carb) comes into operation sometimes when stopping for traffic light ect.

I've had it professionally looked at and (personally, twice) blown thro' fuel pipes from tank outlet thro' to both carb float heads

I can't get hold of any other float carb heads at the moment (Sod's Law)

I've had the float needles and seats changed and cleaned out debris in both float chambers/bowls

Anyone any other suggestions please as we don't want to go on tour and be smelling petrol I had enough of that with the GT6

Checked (electronic) pump, pressure wasn't fantastic but adequate, the pump was fitted new by me in Set '07 (a couple of months after getting the car even tho' the old seemed to be fine but looked outwardly possibly old so I took no chances)

[Snake the Sniper]

I had this problem with an MGB GT once. Does the float actually float? They can fill up a little over time and not shut the valve fully. Or the float height could be just a little out.
You could always just run a return line to the tank. It wouldn't matter that way what it does.

[SB - Nigel]

Snake the Sniper said:

I had this problem with an MGB GT once. Does the float actually float? They can fill up a little over time and not shut the valve fully.

Hi Simon, yes I've checked that three times (and that was only today)

Snake the Sniper said:

Or the float height could be just a little out.

this is the later type

[quote =Snake the Sniper] You could always just run a return line to the tank. It wouldn't matter that way what it does.

easy said than done, my mate also suggested motor bike carbs - bike bits on a car !

No everything worked fine until a couple of weeks ago so I need to find out why

Of course I did think about replacing carbs with new but "you can always fix Su's no need for new" I was persauded - doh!

Thanks for your reply tho' - I've given up for today it's too hot out there folks, dont believe 21 degrees it was that yesterday and todays a lot hotter

[Steve_D]

What pressure is the pump running at?
If the regulator has some muck in it you could be running a high pressure which is overcoming the float. Should be looking at no more than about 6psi.

Steve

[SB - Nigel]

Steve_D said:

What pressure is the pump running at?
If the regulator has some muck in it you could be running a high pressure which is overcoming the float. Should be looking at no more than about 6psi.

Steve

Steve thanks for your reply, we checheck the pump on a meter (can't don't know pressure, it was low but adequate - pump is fairly new electronic

[skeggysteve]

Have you tried bending the part on the float that pushes on the needle so that it puts a bit more pressure on the needle.

Obviously it will lower the fuel level in the carb so is just a temporary get you home (or around Scotland) fix.

[SB - Nigel]

skeggysteve said:

Have you tried bending the part on the float that pushes on the needle so that it puts a bit more pressure on the needle.

Obviously it will lower the fuel level in the carb so is just a temporary get you home (or around Scotland) fix.

Hi Steve thanks for your reply, it's not that sort of float mech (I think)

Tonight the problem has gone away (not resolved) and more pressing problems need to be sorted (why now!)

Plus my friend is back and has given me a set of carbs to cannibalise or transplant as much as I want

I relearnt things today I souldn't have forgotten about fixing cars (which is why I try to avoid it as much as possible)

[Mr2Mike]

SB - Nigel said:

[Hi Steve thanks for your reply, it's not that sort of float mech (I think)

What sort of carbs are they? Should be twin HS2's on a Midget surely?

[SB - Nigel]

Mr2Mike said:

What sort of carbs are they? Should be twin HS2's on a Midget surely?

Hi Mike, yes HS2, unless I'm got the wrong end of the stick which is highly possible, mine have a pin hidge to the float that appears to me as non-adjustable see AUD 662 spares

I favoured a worn groove with the float needle but I struggled to get the pin out that hold the float (lack of confidence no doubt) so I put the magnifying glass back and gave up on that for the time being

[annodomini2]

Is it happening on one carb or both?

[SB - Nigel]

annodomini2 said:

Is it happening on one carb or both?

Hi Andy, only the front has an overflow apetutre but no pipe connector so the petrol runs over the float lid and down the side of the bowl - nice

[Snake the Sniper]

Exactly the set up I had on the MG. And also precisely what went wrong. Only thing is I never did fix it, as I sold the car before I got round to it! Just bung a new cover/float top bit on and see what happens.

[skeggysteve]

SB - Nigel said:

Mr2Mike said:

What sort of carbs are they? Should be twin HS2's on a Midget surely?

Hi Mike, yes HS2, unless I'm got the wrong end of the stick which is highly possible, mine have a pin hidge to the float that appears to me as non-adjustable see AUD 662 spares

I favoured a worn groove with the float needle but I struggled to get the pin out that hold the float (lack of confidence no doubt) so I put the magnifying glass back and gave up on that for the time being

Looking at the picture it would appear that you can't adjust the float height - I just assumed you would be able to, sorry.

The pin is just a push fit, well it always has been in my experience!
They can be tight to get moving but do pull out. Might be worth trying from both ends of the pin.

[SB - Nigel]

Cheers lads now I've got a spare set of carbs to play with I'm settled

I could take the pin out now with the help of a magnifying glass (Mr Magoo)

Most people have assumed the carbs had the adjustable forked arms which shows they know about even older cars than mine