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SU Carb overflow tubes

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Jim_Gruber

Jim_Gruber

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After seeing the note posted about almost burning BE up due to leaking gas flow overflow tubes I am pondering. IS it normal to run SU Carb overflow to a rubber hose and down to underneath car. Bugsy my '68 with 1098 does not have any sort of overflow tube in place and I do notice the small of gas emanating from under the hood at high speeds. Got the low speed smell gone, just noticing at higher speeds. Trying to figure out if I have a leak or smelling raw gas from too rich exhaust fumes.

Are you using any sort of Right Angle adapter on the hose or clamping on and running underneath the car.
 
Early carbs just had vent holes. Later ones had tubes running to the charcoal canister for vapor collection. I no longer have the vapor collection setup so I run mine to a tube that would drain on the opposite side of exhaust.

There should be no fuel running through these lines and the vapor would be very minimal.
 
Trevor, 100% concurrence on fuel vapor but still, a drop or two puts out a lot of odor. I retightened all of my carb and manifold bolts and that seems to have cured the low speed intermittent odor. Seemed to occur when I would turn off the choke.

Now getting out and running 55-60 for less than 5 minutes and I smell gasoline. Cannot find it in the engine compartment but perhaps overly rich condition right now might be a contributing factor. Have gone from dark black and sooty to medium brown and working my way down slowly one flat at a time.
 
Trevor, 100% concurrence on fuel vapor but still, a drop or two puts out a lot of odor. I retightened all of my carb and manifold bolts and that seems to have cured the low speed intermittent odor. Seemed to occur when I would turn off the choke.

Now getting out and running 55-60 for less than 5 minutes and I smell gasoline. Cannot find it in the engine compartment but perhaps overly rich condition right now might be a contributing factor. Have gone from dark black and sooty to medium brown and working my way down slowly one flat at a time.
 
I posted about my Bugeye almost burning down. To be honest with everyone, I haven't fully investigated the cause. I know that once the fire was out I saw the tube removed from the vent hole and just made the connection.....it may or may not be the cause of the fire.

I was gone all day today, so I haven't had the chance to even look at the Bugeye yet, but will post what I find as soon as I can.
 
Rubber line are not a bad idea, I'm not fond of hard lines, the key the to do is make sure how every you attach them that they have enough play in the them that when the engine is torqued, they do lean a bit under acceleration, that the line are not pulled loose. The holes or tubes are a vent for the float bowl, no vent and the float lid would pressurize, the only time fuel would ever come out of vent is if the needle and seat valve sticks close or the float takes on fuel.

The flaot lids with just the vent hole, do not give you the option of the runing a line, but you ca change your flaot lids to the one that do have the tubes. This may require you to rearrange your fuel delivery lines.
 
Thanks Hap, a project for another weekend. Kelly, Fuel Pump is not leaking. I've been all over back there as I recently dropped the tank several times to replace sending unit. Fuel Pump was replaced this year but I've redone and retightened several times. I'm sure it's not coming from back there.

Hap would you recommend changing from Gross Jets to the Vitron Tipped float seats? When I was having some other issues I changed the tops/floats of my SUs to the ones off of my later '69 spare 1275. The carbs themselves are what came on 66 vintage 1098 that came in this car. I simply changed the floats thinking that was an issue when I had a "low pressure" Mr. Gasket fuel pump in there that was actually pumping out 7-8 PSI and pumping gas out of the overflow tubes. Since then I replaced with a true Low Pressure 3.5 psi pump and that issue has gone away other than at higher speed now.
 
Jim, first thing I would do is check inside the float bowls and see if one is over full. if so check the float valve or check for a sunken float.
 
The viton tipped needle and seat valves are the ones I use, none fo them are bullit proof, but the viton units seem to be the favortie of most folks, and the Grose Jets the least favorite of most. As for float I submerge them in a glass of water to check them, they rarely ever go bad.
 
Can I change out the Vitron Tipped Units without changing out the floats? Or does it all need to be changed out as a unit. On the road today and don't have a catalog at hand. Thanks Hap.
 
Valve tips can be changed easy enough without messing with anything else other than the float hinge.
 
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