Internal carb leak, 51 Cambridge

[motoMark]

Ever since I got the car in 2022 I noticed a little wetness on the throttle plate of the carb. Nothing bad, in fact it looked kind of oily, not gas. So tonight I thought I'd take the carb off and have a look. Much to my surprise I found a pretty substantial puddle of gas on the floor of the intake manifold.

 

Has anyone ever come across this before? I know the needle and seat, float, and float level need to be checked once I get the carb back together, but its there anything else I should look for?

 

Thanks,

Mark

[Sniper]

Yes, my 51 Cambridge did that as well.  It was the tip of the needle that was messed up.  I just did a good cleaning and rebuild on it.

 

http://www.yourolddad.com/carb-rebuild

[Ivan_B]

59 minutes ago, motoMark said:

Has anyone ever come across this before?

Yes, this happens all the time, it is overflowing... Also could be doing this with the normal float lever when the gasoline overheats.

Make sure that your float still floats, too. Mine was full of gas.

[Booger]

All good points. Often I check mounting plate nuts for tightness

And that gets a double gasket

[Ivan_B]

1 hour ago, Booger said:

And that gets a double gasket

For heat insulation?

I've got a 1/2 phenolic spacer, which I did not install, yet, because that will require extending the fuel line. Also got a new fuel line but am now contemplating to get the valve-lifter gaskets replaced as well, while I am in there, so I need the gaskets. I've got an excuse for everything

[motoMark]

On 4/5/2024 at 9:46 PM, Ivan_B said:

Yes, this happens all the time, it is overflowing... Also could be doing this with the normal float lever when the gasoline overheats.

Make sure that your float still floats, too. Mine was full of gas.

Luckily my float is ok. Nothing sloshing around inside and floated in a cup of water overnight with no issues.

[Ivan_B]

2 hours ago, motoMark said:

Nothing sloshing around inside and floated in a cup of water overnight with no issues.

If there is no gas inside, it is probably good. The way you quickly test a metal float is dip it into near-boiling water: no bubbles - you are good to go. In this case, just set your level (according to the manual) and make sure that the seat and needle are clean and look alright. I had some kind of curly debris blocking my needle as well. I had to take the carb apart like ~3 times, before I figured out why it is overflowing 🙄

Also, make sure that the float itself is moving freely and that the float shaft lock (push down) clip is in place. We've had a person, on here, who had it missing, resulting in an incorrect fuel level.