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Drain back

According to his original post fuel perculation isn't the problem it's evaporation like every other carbureted vehicle.
 
No 2 motors are identical, simple things like a thicker base gasket, air flow under the hood, thermostat rating, whether or not the heat riders were blocked off in the intake, brand of carburator, type of intake, etc all play a factor.

If it's fuel boiling out of the carburetor the best thing you can do is insulate the carburetor from the source.. the intake.
Wonder what base gasket is being used currently.
 
Percolating causes evaporation. A insulator gasket helps. A Holley carb helps. To a lesser degree, insulating fuel lines under the hood helps as does a fuel return line system helps. The bottom line is the fuel is getting hot enough that it is boiling and then it evaporates and over the course of a few days, the float bowls are damn near empty. You either need to crank the engine over long enough to fill the bowls, squirt some gas down the bowl vents, or hit the momentary switch you have attached to your electric charge pump. You can insulate and isolate like I mentioned above and one or all may help.
 
Percolating causes evaporation. A insulator gasket helps. A Holley carb helps. To a lesser degree, insulating fuel lines under the hood helps as does a fuel return line system helps. The bottom line is the fuel is getting hot enough that it is boiling and then it evaporates and over the course of a few days, the float bowls are damn near empty. You either need to crank the engine over long enough to fill the bowls, squirt some gas down the bowl vents, or hit the momentary switch you have attached to your electric charge pump. You can insulate and isolate like I mentioned above and one or all may help.
The puzzling part is the op stated it only took 1 day for the gas to be gone.
 
The puzzling part is the op stated it only took 1 day for the gas to be gone.
I have had mine dissappear that fast. Not from putting around town though. Heat soak is the issue.
 
Percolating causes evaporation. A insulator gasket helps. A Holley carb helps. To a lesser degree, insulating fuel lines under the hood helps as does a fuel return line system helps. The bottom line is the fuel is getting hot enough that it is boiling and then it evaporates and over the course of a few days, the float bowls are damn near empty. You either need to crank the engine over long enough to fill the bowls, squirt some gas down the bowl vents, or hit the momentary switch you have attached to your electric charge pump. You can insulate and isolate like I mentioned above and one or all may help.
I wasn't going to say it because nobody likes hearing it but yes Holley's do better with heat related issues. Carter's have a bowl that's part of the base (direct heat transfer) where Holley's have the bowls at both ends with 4 gaskets separating the bowls from the source.
 
I find it hard to believe that the fuel is evaporating in just one day.................even 10% ethanol shouldn't evaporate THAT fast. Hell, there are only 2 little vents.

What temp thermostat are you running?
What is your normal operating temperature?
 
I find it hard to believe that the fuel is evaporating in just one day.................even 10% ethanol shouldn't evaporate THAT fast. Hell, there are only 2 little vents.

What temp thermostat are you running?
What is your normal operating temperature?
180 thermostat, the highest I've seen it so far is 185. But it's a new engine with just a couple hours on it.
 
180 thermostat, the highest I've seen it so far is 185. But it's a new engine with just a couple hours on it.
What base gasket are you using and what is the length of the fuel pump pushrod? I had similar symptoms until I found that both needed to be changed.
 
What base gasket are you using and what is the length of the fuel pump pushrod? I had similar symptoms until I found that both needed to be changed.
Push rod measured 3.24 inches. Using a 1/8 inch thick metal spacer plus a standard composition gasket.
 
Push rod measured 3.24 inches. Using a 1/8 inch thick metal spacer plus a standard composition gasket.
Since you're using an Edelbrock carb I would suggest the Edelbrock 9266 base gasket. I use that with my original AVS and never have heat related fuel issues.
 
Edelbrock makes the wooden spacers. I have the 1/2" on mine. No problem with heat soak and I'm using an antique cast iron manifold. (Crossover blocked off)
20210720_165143.jpg
 
What base gasket are you using and what is the length of the fuel pump pushrod? I had similar symptoms until I found that both needed to be changed.
I'm just using a pair of basic carb gaskets.
Never measured the push rod when I had it out to install the cam. No problems, so I guess it is still within spec's.
 
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