Fuel Overflow

[Gary H]

What makes gas drip from one of the two small copper/brass tubes from the manifold when the engine is shut down? It also drips as the fuel pump comes on prior to starting. Both HD8 carburetors recently rebuilt, including new floats. My first thought is the floats are not adjusted correctly.

Any other reasons?

66 Healey 3000

 

[Michael Oritt]

Yes, float levels are off, allowing gas to pool in the manifold.

 

[steveg]

Sounds like leaking float needles. Joe Curto and Tom Bryant like the viton-tipped needles.

 

[Michael Oritt]

"Sounds like leaking float needles."

Or that. Just one more argument for my proposed line of clear plastic items that would allow inspection in dynamic applications:

1. Clear plastic float bowls so we can see what the fuel level actually is with everything buttoned up
2. Clear plastic distributor caps so we can see any stray sparks when the engine is running
3. Clear plastic valve covers so we can see the condition of the rocker shaft bushings without getting oil all over the place.

There are probably many more applications others will come up with....

 

[roscoe]

With some of today's composites the "Visible V8" of my childhood might be possible in full scale and actually work. If we could see everything that was amiss we might not ever get to just hop in the Healey and go for a spin. :welcoming:

 

[Keoke]

"Sounds like leaking float needles."

Or that. Just one more argument for my proposed line of clear plastic items that would allow inspection in dynamic applications:

1. Clear plastic float bowls so we can see what the fuel level actually is with everything buttoned up
2. Clear plastic distributor caps so we can see any stray sparks when the engine is running
3. Clear plastic valve covers so we can see the condition of the rocker shaft bushings without getting oil all over the place.

There are probably many more applications others will come up with....

I doubt ifin this gonna help the old folks much---LOL

 

[Gary H]

Thanks for the advice. I will re set the floats. I'm not sure I want to see everything that may go wrong!

 

[Bob_Spidell]

You'll get some dripping if you use enrichment ('choke') on a cold day and don't get the engine up to running temp for a few miles. The enrichment mechanism is there to overcome 'wall wetting,' when fuel condenses on the inside of the manifold and doesn't make to to the cylinder. If this excess fuel isn't given a means to escape you could have a nasty carb backfire and, possibly, an engine fire.

 

[Keoke]

You'll get some dripping if you use enrichment ('choke') on a cold day and don't get the engine up to running temp for a few miles. The enrichment mechanism is there to overcome 'wall wetting,' when fuel condenses on the inside of the manifold and doesn't make to to the cylinder. If this excess fuel isn't given a means to escape you could have a nasty carb backfire and, possibly, an engine fire.

Bob:

You just justified why the bends in the drain tubes should never be sharp ones , only very gentle bends.

 

[vette]

Gary, there are two sets of copper/brass tubes coming off of the engine. One set is coming from the carburetor float bowls and these are overflow/vent tubes for the float bowls themselves. The other set of tubes is coming from the underside of the intake manifold. Bob has stated it correctly about these tubes. They allow some venting or drainage if excess fuel get puddled in the intake. This is a natural occurance at times as an example given by Bob. If the fuel weeping is coming from the intake manifold tubes I would not necessarily reset the floats. Many times it is because of the chokes being on and an over rich mixture. If the weeping/drainage/leaking is coming from the tubes off the top of the full bowls then it is because the float needle valve is not sealing. Usually just cleaning or replacing the needle valve will solve this, not necessarily changing the adjustment to the float level.

 

[RAC68]

Hi All,

Vette presented a very good analysis and suggestion with Bob identifying the usual cause of manifold weeping. In these days of drastic swings in ambient temperatures, condensation and water vapor buildup in fuel is becoming quite common. I would also suggest that this vapor could be causing additional issues on startup and also suggest adding a "Dry Gas" product to your fuel. Keep in mind that fuel condensation on cold internal surfaces, as has been mentioned, will be present on startup and, in excess, will take longer to evaporate with engine heat. Also, on shutdown in cold weather, excess operating vapor will also condense quickly and build on these same internal surfaces. Since, on the East Cost, we seem to be in an unsettled atmospheric environment with it being 2F one day and clost to 60F the next, I would not over-analyze or over-act in developing a correction until the atmosphere settled down, cold or warm, and you run the car so your fuel is better mixed (water in gas) and circulated.

Just my thoughts,
Ray(64BJ8P1)