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MG Midget and Sprite Technical - HIF6 help needed

Hi All,

I am currently trying to convert my 1275 midget to a single HIF6 carb without much success :-(

I bought a sold as seen HIF6 K&N filter and standard alloy Metro manifold off eBay.

The float had a hole in it and it had a stange needle in it so I have bought a new float and BDL needle.

I have set the float height 1mm below the bottom of the carb base according to instructions on the net.

The car starts up fine and runs but is running to rich I have screwed the jet right up to the top as far as it will go and sticking out past the top of the bridge but it still wants to be leaner.

If I try and increase the revs they build up but at about 3000 RPM it doesn't sound happy and the dashpot is moving up and down of its own accord.

If I look into the carb mouth I can see loads of fuel spraying up, and it doesn't appear to be comming from the jet, if I take the dashpot out then there are two holes just downstream of the bridge it looks like fuel is being sucked out of one of these somehow ? Or maybe I am just barking up the wrong tree.

Anyway I am out of ideas short of sealing these holes up ? what are they for anyway.

There is oil in the dashpot, the piston is free to move up and down OK not catching anywere, if I push up on the little plunger to the side then the revs rise and stay high for too long indicating a rich mixture.

Looks like I am going to have to buy another carb :-(
Ben Brown

This could indicate that the integral choke mechanism is letting fuel through unrestrictedly, is the choke lever turning shut or not?

Or the needle valve may not be shutting off the fuel when the float is at its level

It looks from reading the Haynes SU Book that the holes inward of the jet hole are supply jets for cold starting

HTH

Bill 1

Hi Bill, Thats good info, no my choke lever is not fully shut as the choke cable is a little short, I wound the fast idle back but couldn't see that the lever was doing much else, I will disconnect it and see if it makes a difference. cheers Ben.
Ben Brown

Bill's right.
One of those holes is the discharge for the cold start, so if it is that one then the choke is ON, or the o-rings in it are defective. The other hole is a vent from the float bowl, so if it is that one spewing then the float level is high, float valve bad, etc.
I once had an MGB with little screws in those holes - ran funny! And thoughts of them falling out then in were awful.

FRM
FR Millmore

Disconnected the choke lever and still the same it was only on a tiny bit

Definately fuel spewing out of that hole though

Took the carb off again and dismanteled the choke lever assembly and sure enough the same numpty that had holed the float seems to have also been here too. The O ring had been put in wrong and was now split in two and not sealing at all.

A trip to my local plumbers merchant got me a new O ring for 58p fits a treat not sure how petrol resistant it is though we will see

Now running lovely very pleased :-)

Thanks for your help.

Ben Brown

Took her for a spin this afternoon.

Running very nice, quite, smooth and crisp compared to the big weber with all the wrong internals.

Even idles nicely which makes a big change
Ben Brown

Fletcher, that was a scary thought. Good job you found that out

Ben I'm all glad it was such a simple problem to deal with, split O-rings can be a right bugger.

Never know, could be any of us next

Mind you I do have a huge box of O-rings already :-)
Bill 1

The O rings don't need to be split. Even if just a bit of a flat wears on them, then the fuel enrichment device (choke) leaks fuel.
Guy Oneandahalf Sprites

aha!
Bill 1

Plumbed in my vacuum advance for the first time and with great excitment checked it out with my strobe light.

Didn't work, the vacume unit is ruptured, rats.

Looking at cheap dizzies on eBay

£28 for a complete points version new
£53 for a complete electronic version new

Trouble is with the milage I do it will take me 5 years to recover the costs in fuel savings for the points version let alone the electronic one

Cant help thinking at that price they must be chinese last 5 minutes rubbish too

Anyone got a working vacuum unit for a 45D4 Lucas looking for a good home ?
Ben Brown

I've seen vacuum units on their own on ebay recently...
David Smith

The scrapyards used to be full of A-series Rover Metros with electronic dizzies. My MG metro one cost £5 including a few spare plug-in modules. An excellent modification for maintenance free easy start and smoother running. Worth looking out for.
Guy Oneandahalf Sprites

The cheap dissys available at the moment are great value for money. I bought one a year or so ago for my MGA and it is first class.

By the way the Chinese only do as they are told. Our suppliers know what we are prepared to pay so they get the work and parts made to that budget. It does not work the other way around we get what we demand.
Robert (Bob) Midget Turbo

This thread was discussed between 29/10/2010 and 31/10/2010

MG Midget and Sprite Technical index

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