Leaking Float Bowl Question

[Monark192]

I am trying to make sure my 74 Midget is good to go for the San Diego rolling British car day April 13th. The float bowl on the front carb is leaking fuel. Is this simply a question of replacing the gasket or something more involved with the carbs??

 

[Trevor Jessie]

Is it leaking where the jet tube is attached or around the lid?

 

[jlaird]

Or is the float stuck or too high??

 

[zimmy]

sounds like its stuck and flooding.....
common problem....
rebuild them if u havent already..z

 

[Monark192]

I think it is just around the lid. I don't see it leaking when the car is running but there is sticky fuel residue over the bowl and on the jet tube at the bottom.

 

[jlaird]

Clean it up and put a new gasket on. Easy enough, see what happens.

 

[Monark192]

I will replace the gasket and see what happens. I have had one MG catch fire on me and so I am a little nervous around fuel leaks.

 

[jlaird]

As you should be. However, this leak is going to show quickly till you get it stoped.

 

[DrEntropy]

If a couple sharp taps with a screwdriver handle doesn't cure it, it may be needle and seat R&R time. Hap here onna Forum or Joe Curto. And Viton tipped. NO "Grosse Jets"!! :wink:

 

[Monark192]

Hap has done a rebuild for me before on some MGB carbs so I am familiar with his great work. Only 10 days until the British car day though so I will try a gasket and hope for the best.

 

[DrEntropy]

With the lid off, check the float to be sure it hasn't started leaking, and check/clean needle and seat (Q-Tip and some carb cleaner are fine). Double check float travel and drop height while it's apart. Too easy NOT to do then.

 

[Monark192]

Doc,

Just as soon as I figure out what you just said, I will get right on it!

I'm not affraid to tackle much on these cars but the working of the carbs has always been a bit of a mystery to me.

 

[healeyboz]

These carbs are no big deal. Just pull them apart and have at it. Anything else can be helped with on here.

 

[jlaird]

What Doc said:

Take the top off the float chamber and check that the floats float, drop the valve out and clean the seat with a q tip and carb cleaner. The seat is in the top of the float chamber cap.

Check and adjust the float slack in accordance with the manual for your type carb. Prob is an 1/8 of an inch under the arm but you really need a shop manual to see how it is done.

Enjoy.

 

[Billm]

Do not rely on the upper gasket to stop a leak! It may stop some small "sloshing" leaks but it will NOT stop a leak caused by a sticking float valve or a misadjusted float. I consider the top gaskets "decoration" and nothing more.
Bill

 

[Hap Waldrop]

I'd replace the needle and seat valve as well as the bowl gasket, a five mniute repair, and the most common problem. Some SU float bowl lids have a brass tube for a vent tube line in which you can put a line on for any leakage coming from this point, but alot of the later SU float bowl lids only had a small hole for the vent in the lid with a little aluminum dust guard over them, if you have that type vent on your float bowl lid, that could be the leak you are seeing, which would mena you have a stuck needle and seat, the parts are cheap repalce both, and before you order the parts, sumerge check your float to make sure it doesn't have a hole in it, if any question repalce it to, then you got it covered, all the part are cheap and it only take a few minute to make the repair.

 

[jlaird]

Nothing will stop a bad or sticking float leak as there is a hole in the top of the float chamber to let the overflow out if it happens. Yep gasket just for slosh.

Or even in the case of early carbs a special line that runs to below the engind to keep any leakage off of the exhaust.

 

[Monark192]

Thanks for all the advice. I will take the carb apart when the gasket arrives, have a look around and ask for help here if needed. My carbs have the little brass vent tubes - should there be an overflow tube attached??

 

[jlaird]

The vent tube on the early carbs was a kind of banjo fitting at the top with a copper tube that bent down toward the ground. about 14 inchs or so long.

Latter models had I think a rubber hose that went down and still later had only a breather hole in the cap with no vent tube.

 

[bugimike]

On the later carbs it is quite simple to create a home-made tubing set to route any overflow to the bell housing and back down to avoid fuel spillage onto the hot exhaust!