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MG MGB Technical - Sunken float

I noticed the MGB was running rough today, and pulled the plugs to find them black. Cleaning them didn't help the car run any better, nor did checking the air filter - clean. I then suspected the floats, and sure enough the front one is full of fuel.
The carbs are HIF-4 carbs, purchased used and installed three years ago without any modifications. They are installed on a 1977 MGB. The carbs don't have the aluminum tags under the dashpot screws so I'm not sure what they are exactly. I believe they were all the same from '72-'74.
The replacement floats for the HIF-4 carbs in Moss appear slightly different in the picture. Will they work?
Is there a way to identify the carbs?
The needles appear to be OK, but should they be replaced anyway?
I think I'll buy rebuild kits and do it now or over the winter just to be done with it for a while. But for now I may just install the new float. Any concerns?
By the way, up until now the car ran great. And the weather is finally feeling like summer, so I want to get it back on the road as soon as possible.
Thanks for any advise.
Randy
1977 MGB Tahiti Blue
randy olson

Randy, If the carbs have a notch in the throttle plates they should be AUD493 from a 72, no throttle plate notch should be AUD550 or AUD630 from a 73 or 74. The floats should be the same in either carb. Clifton
Clifton Gordon

The throttle plates have been soldered closed where the holes were. Is that what you mean by NOTCH?
Thanks for the quick response! This forum makes owning an MGB a lot easier.
Randy
randy olson

Randy, I guess you got through the altinator issues last winter and have been enjoying Ithaca summer. Best time to be in the Finger Lakes. Floats are interchangable as Clifton says so get it back on the road before the October snow! Are the bloodies still as good as ever at the Glenwood Pines? Give my regards to Davy!

Paul '82
Paul Hanley

Paul,
Yep, the starting problems were finally traced to a faulty battery connection. The positive pole connector was completely corroded to the point where it wasn't making good contact. I had to jump through several hoops before isolating the problem. Just confirms my adage: Check the simple things first.
The MGB was running great, complete with a new-to-me radio/cassette and speakers thanks to my sons who both upgraded their systems. It will be on the road as soon as I get the new float, and I'll have a bloodie at the Pines for you!
There's no way to repain the plastic type floats is there? I repaired the brass float in the SU's on my Jag last fall, and they've been fine ever since. I may give it a try...nothing to lose.
Cheers,
Randy
randy olson

Randy, If you have a Haynes MGB manual look at the HIF exploded view on page 79. The throttle plate item #37 has a barely visable notch at the bottom of the plate. If you don't have a notch in yours your carbs should be AUD550 or AUD630. Clifton
Clifton Gordon

Randy, I personally would not attempt a fix unless I was stranded on the side of the road. If that were the case I's try permatex 1A--it's fuel resistant or a little JB weldbond. In either case you's need to rough up the surface around the leak--if you can id that location.

Certainly more prudent is to order one from Moss before 3:oopm to insure same day shipping. Since more than likely it will come from NJ, you'll have it the next day, or at the earliest now, Monday.

As far as a rebuild this winter, I wouldn't. If it ain't broke....

Paul
Paul Hanley

I "fixed" a plastic float as a temporary measure. Per Paul's comment, this is my daily driver and I have no other transportation if the MG is laid up.

I drilled a small hole where the crack was which allowed me to drain the fuel from the float. Then I plugged the hole with a small brass machine screw and a little fiber washer. It was strictly temporary until the new float could be ordered and shipped. I think I ran it that way for a couple of weeks. It worked okay, but I felt like a real DPO.

Matt Kulka

This thread was discussed on 03/09/2004

MG MGB Technical index

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