Can I just seal off my carb overflow

[Natenate4s]

Hello everyone. I had some carb overflow and it was quite a bit. My floats do float and I don't feel any gas inside them when I shake them. I adjusted the float level and I haven't had overflow, but now I'm worried about a fire. The overflow tubes are broken off. I've read we can run some lines down under the car, or inside the air filter somehow. But is letting the gas just run out onto the street really the best option? Can I just seal them off instead? What could happen if I just seal them off?

[pebbles]

NOOOOOO. Something is wrong if they are overflowing. Find some good ones or repair them. Route them low. Make sure you have ZERO exhaust leaks, a new fuel filter, and good spark plug wires.

[fj20spl311]

If you seal them off. the fuel will run into/out of the carb and then into the engine or into the air filter. Either of which could cause a fire.
It might also be possible to cause a hydro-lock of the engine if the fuel fills the combustion chamber which could bent a rod or blown the head gasket.

IMHO, extend the hose to below the frame or into a catch can and check often.

[Natenate4s]

Ok. Glad I asked! This was the only time I've seen it do this. It's stopped, for now. Lol. I don't know why it did it or why it stopped. I'll run some lines underneath the car into some sort of catch can.

[Natenate4s]

Can I just run the two lines into a fuel filter underneath the car? This way it's all sealed up? Or does it need to be able to flow out?

[msampsel]

Can I just run the two lines into a fuel filter underneath the car? This way it's all sealed up? Or does it need to be able to flow out?

I'd recommend just running rubber gas line down below the frame away from the exhaust. As you said it does not happen often.
Sticking floats have caused mine to spew.

If you run to a filter sealed up and it fills then you have them sealed and the catastrophic possibilities Phil spoke of may occur

[Natenate4s]

Ok. Sounds like a plan

[Natenate4s]

How do I make a catch can? Does anyone have a pic?

[Nissanman]

Here is a pic. of the OEM fuel overflow pipes: -

carboflowtubes2.jpg

They are long enough to vent below the level of the exhaust headers.

A catch can is fairly simple device: -


http://www.ebay.com.au/itm/Red-Cylinder ... 1e7d748620

Normally used for blow-by gasses though, I wouldn't use one to catch fuel.
It would become a bomb waiting to go off

[Natenate4s]

Ok. I don't think I'll use one of those. Lol. I ran my lines down, to the outside of the frame, then into the support section that has the holes in it (hope that makes sense). I was going to have it run down and out from there but I got worried gas would blow up onto the muffler.

[msampsel]

Here is a pic. of the OEM fuel overflow pipes: -

carboflowtubes2.jpg

They are long enough to vent below the level of the exhaust headers.

A catch can is fairly simple device: -


Normally used for blow-by gasses though, I wouldn't use one to catch fuel.
It would become a bomb waiting to go off

I just spent a wonderful 20 minutes scanning all your restoration photos Nissanman ! Wow makes my work feel like this
. Trying to see if you have oem overflows or not (nosy I am). I've never seen them intact!
At least your temp sender is on the correct side .

[68DSU]

Environmentally it is probably a bad thing to let gas spill out on the street but safety wise it might be best. Gas will evaporate quickly and as you are moving, it will be away from you and your flame inducing exhaust. Catching it and holding it will only cause that bomb as your container would fill with fumes. The fumes are more dangerous than the liquid and keeping it in a container just lets it concentrate. Keeping that container with you will result in an insurance claim, if not by you, then by your survivors.

[fj20spl311]

A catch can is no more of a bomb than the carbs are a bomb.

A quart of vapor makes a fun pop at best....a pint, not even worth talking about.

[Natenate4s]

Ok. I'll let it run out to the street then. Thanks for the feedback everyone.

[Nissanman]

I had to manufacture the two overflow pipes, mine were busted off right at the banjo connection, as usual
It was so much fun shaping and threading them down the side of the engine to my reproduction pipe guides that mount under two sump fasteners.
It all looks stock but it was all hand made to the detail in the parts manual