The fuel magically disappears from my carb!

[khryslerkid]

Here are the results of another little test I did in order to get a better handle on this question. I took one of those magnetic parts dishes you use to put nuts & bolts in when disassembling things. It's was 3 1/2" in diameter and I put 1/4" of gas in it at about 1000 hrs. By about 1800 it was down to 1/8" and by this morning it was all but dry. Now I'm not sure how the open surface of the parts dish as opposed to the surface area of the float bowl with only a vent would affect the evaporation rate, but I think it is safe to say that fuel evaporates pretty damned fast. Faster than I would have guessed.

Yes and add about 200 degs to it and watch it go.

If the two sides of the Eddie are connected it must be by very small passages as when I filled one side to measure the volume, I didn't notice any seeping to the opposite side. I do know they are connected by the top plate for fuel supply.

 

[threewood]

Yes and add about 200 degs to it and watch it go.

If the two sides of the Eddie are connected it must be by very small passages as when I filled one side to measure the volume, I didn't notice any seeping to the opposite side. I do know they are connected by the top plate for fuel supply.
View attachment 511435

There is a crossover passage behind the secondaries in your picture as well. On the AFB, there is only one fuel inlet. On the AVS Thunder there are two, just like a double pumper but it still retains the passage in the base.

Heat is the culprit no doubt. I'm in AZ so I just deal with it as I really like the design and simplicity of adjustments. I just recently went to an electric pump which has the effect of removing the mechanical pump which acts like a heat sink. That plus heat shielding and a 1/2" phenoletic spacer and my fuel lines are now much cooler than before. Plus I am mixing in 5 gallons of Sunoco 110 race gas to keep the fuel more stable. My 440 puts off way more heat than my 318, which seems to keep fuel up top longer.

 

[khryslerkid]

There is a crossover passage behind the secondaries in your picture as well.

That passage is about the height of the fuel level in each bowl.

 

[threewood]

That passage is about the height of the fuel level in each bowl.
View attachment 511454

I've never figured out the need for it. Both bowls are vented and the inlet feeds both sides. I have read that a stumble or stall going around corners is caused by fuel rushing from one side to the other.

 

[Ranger16]

That trough has to be the crossover feed for the other side. I did not realize that it was so shallow though. Thanks again for that picture Kid. All the more reason to prime both sides.

 

[coloradodave]

Interesting idea. I have seen racers connect the two bowl vents with a rubber hose. I wonder how well that works.

Yes, Mike. On Holleys you can connect both bowl vent tubes with a short piece of 1/4" hose. At the top of the 'arc', you need to slice the hose (sideways, taking just enough off to expose the ID) so that they are still vented. This is to prevent fuel from running up the tube and dumping down the venturies under violent acceleration when the carbs are mounted inline (front to back). If mounted sideways, as on a tunnel ram for instance, there's no need. Holley sold vent extensions to try and cure the problem, but hose is cheap, and works. If you run an air filter, the lid becomes problematic...

 

[moparedtn]

He he!
You can try a ketchup bottle but you'll probably spill gas all over the place trying to hit those small holes. I like the newer mustard bottle for the small nozzle on it. They're even a bit transparent so you can see what's in it.
View attachment 511371

I got the idea years back, running with a Super Comp team. It was convenient for reaching into the scoop and giving the toilet bowl a good shot for fire up. Alcohol dragster.

I don't remember but you're running the stock cast iron manifold? Crossover blocked?

Yep on the manifold. Nope on the crossover.
Engine was assembled when I got it and the crossover part of the intake is already cooked and peeling off.

 

[moparedtn]

Some carbs are more prone to the issue than others. Another thing you can do that will help a little is to block off the heat riser to the intake. Mother Mopar has the intake bath tubs with it blocked off for the b motors. Most likely they have them for the la motors too. This will help keep some of the heat off the intake.

I might pull the intake off the critter just to do this, even with my recent experiences with that (on the previous engine), where machining made for bad fitment of the intake against the heads.

 

[khryslerkid]

Yep on the manifold. Nope on the crossover.
Engine was assembled when I got it and the crossover part of the intake is already cooked and peeling off.

Thats definitely a contributing factor. But you know this.

Do you have any e free gas in your area? That's what I'm useing as long as I can get it.

 

[moparedtn]

Thats definitely a contributing factor. But you know this.

Do you have any e free gas in your area? That's what I'm useing as long as I can get it.

There's one place local that I used to use, but after dropping the tank one time and seeing the downright yellow and nasty condition of the gas I bought there less than a week earlier, I don't go there anymore.

I wonder if something like StaBil would help any?

 

[khryslerkid]

There's one place local that I used to use, but after dropping the tank one time and seeing the downright yellow and nasty condition of the gas I bought there less than a week earlier, I don't go there anymore.

I wonder if something like StaBil would help any?

I know StabBil helps with preventing corrosion and gum. It's designed for engines that normally use e free gas. Wouldn't hurt.

You know the owners manual for my 2003 hemi says not to use ethanol gas! What do you think about that?

 

[moparedtn]

I know StabBil helps with preventing corrosion and gum. It's designed for engines that normally use e free gas. Wouldn't hurt.

You know the owners manual for my 2003 hemi says not to use ethanol gas! What do you think about that?

I wouldn't doubt it a bit.
It's an inferior fuel in regards to potential energy (and therefore, fuel economy and power).
The small engine industry never got with the e-fuel program, either. The stuff eats the carbs and fuel lines right outta them.

 

[toolmanmike]

How about one of these hooked to a toggle or momentary push button? Will it free flow if not running? I like the small inline size and the 4# limit. It just needs to be a charge pump.

https://www.summitracing.com/parts/crt-p60504/overview/

 

[toolmanmike]

Here's a capture from a FABO thread. Might be helpful.

 

[khryslerkid]

Maybe a dumb question (but sometimes it's the one you never asked) can fuel flow through a mechanical fuel pump when the engine isn't running? Will useing a electric pusher pump work useing the two together and would the electric one be a restriction?

 

[toolmanmike]

Maybe a dumb question (but sometimes it's the one you never asked) can fuel flow through a mechanical fuel pump when the engine isn't running? Will useing a electric pusher pump work useing the two together and would the electric one be a restriction?

I asked the same thing.

 

[ckessel]

He he!
You can try a ketchup bottle but you'll probably spill gas all over the place trying to hit those small holes. I like the newer mustard bottle for the small nozzle on it. They're even a bit transparent so you can see what's in it.
View attachment 511371

I got the idea years back, running with a Super Comp team. It was convenient for reaching into the scoop and giving the toilet bowl a good shot for fire up. Alcohol dragster.

I don't remember but you're running the stock cast iron manifold? Crossover blocked?

Excuse me, but do you any "Grey Poupon"?

 

[Billccm]

I wonder if something like StaBil would help any?

I'm using StaBil 360 as recommended by the seller of my Road Runner. The 360 is supposed to address ethanol specifically in carb vehicles. It's not 5 year StaBil, but 360 day StaBil. It might be snake oil, but O'Rielly has sales from time to time for $14 for two bottles, so it is not a big expense. I put 4 ounces in at each fill up.

 

[Billccm]

https://www.goldeagle.com/product/sta-bil-360-performance

 

[Billccm]

Slightly off topic; I listen to a auto repair talk show that is local on Saturday mornings. The mechanic on the show recently recommended that a caller storing an old Mustang spray the carb with WD40 when he shut it down for the storage period. He said to spray into the vents, throttle horn, and even the outside of the carb with a good soaking of WD40. According to this mechanic, he does it on all of his classic cars that don't get driven often.