Edelbrock 1405 Help

[middleagecrisis]

I don’t recall this being an issue before I recently rebuilt the carb, but honestly, the car set for a while not being run while I was doing maintenance on the motor. This is on a mildly built 318 with headers and an aluminum intake.The motor is very difficult to start after it’s set for about 15 or 20 minutes. it seems like the motor is flooded and boiling fuel over into the intake after it sits for more than a few minutes. To try and combat this I installed a phenolic (1” open & 1/2” 4 hole under the carb) spacers. I’ve also tried adjusting the flow levels to 7/16” as recommended by Edelbrock, and then 1/2”. The float drop is set at 1 inch and my fuel pressure measured at idle is 4 psi with a stock, mechanical fuel pump. When I rebuilt the carburetor, I blew out all passages with carb cleaner to make sure that there was no obstructions in the channels. Any ideas why fuel might be siphoning out of the carb when it sits? The motor runs very good throughout the RPM range, I just have this initial problem at hot start. I’ve searched the forums for any problem similar to this and it seems like I’ve done everything suggested. Thoughts?

 

[Big.J.007]

I had a very similar issue with this model of carb years back.. It was swapped for a thermoquad and later a Holley. Never looked back.

 

[toolmanmike]

I don’t recall this being an issue before I recently rebuilt the carb, but honestly, the car set for a while not being run while I was doing maintenance on the motor. This is on a mildly built 318 with headers and an aluminum intake.The motor is very difficult to start after it’s set for about 15 or 20 minutes. it seems like the motor is flooded and boiling fuel over into the intake after it sits for more than a few minutes. To try and combat this I installed a phenolic (1” open & 1/2” 4 hole under the carb) spacers. I’ve also tried adjusting the flow levels to 7/16” as recommended by Edelbrock, and then 1/2”. The float drop is set at 1 inch and my fuel pressure measured at idle is 4 psi with a stock, mechanical fuel pump. When I rebuilt the carburetor, I blew out all passages with carb cleaner to make sure that there was no obstructions in the channels. Any ideas why fuel might be siphoning out of the carb when it sits? The motor runs very good throughout the RPM range, I just have this initial problem at hot start. I’ve searched the forums for any problem similar to this and it seems like I’ve done everything suggested. Thoughts?

It may very well be vapor lock due to heat soak. Edelbrock/Carter carbs are prone to that because the float bowls are directly above the base and the intake. Heat soak is a real issue with the puppy pee gas we have now days. Non ethanol premium seems to help as well as high octane race gas. Carb base insulation helps as does a fuel return system. The guys that have installed a small pump near the tank with a momentary switch you use only as a primer pump probably works the best.

 

[middleagecrisis]

I’m building a 360 now that will have a 750 double pumper on it and the Edelbrock issue won’t be a problem anymore. I do plan on upgrading the fuel system for the 360 in the future. I’m just trying to get the 318 to run its best to let me have some fun with it before I yank it out. Like I said before, I don’t recall this being an issue before I rebuilt the carburetor. I didn’t even have phenolic spacers underneath the carb before I rebuilt it. I like the adjustability of this carb, just not this hot start issue.

 

[ProjectBazza]

It may very well be vapor lock due to heat soak. Edelbrock/Carter carbs are prone to that because the float bowls are directly above the base and the intake. Heat soak is a real issue with the puppy pee gas we have now days. Non ethanol premium seems to help as well as high octane race gas. Carb base insulation helps as does a fuel return system. The guys that have installed a small pump near the tank with a momentary switch you use only as a primer pump probably works the best.

I agree with Mike (install an electric "primer" pump), as I had to do this on both of my old trucks.

Today's gas sucks, and I can't afford to run "High Test" (non-ethanol) on an 8 MPG truck all the time.

 

[Oldmanmopar]

Your problem is the hot ethanol fuel bubbling will not lift the float to close the needle and seat. You need to put a return on the system as they did on all carbureted engines 74 and newer. If your using a mechanical pump use the style in the fist picture. With a electric pump and a holley style carb use a return pressure regulator and the style in the second pictures.

I had the same problem. I would start it with the pump off and turn it on and off until fresh fuel reached the carb. Once I installed the return it fixed the problem. I always install a return on all mechanical pump cars as seen in the first picture. Problem cured.

My race engine never did it with C16 race fuel. Only when putting pump gas to go to car shows.

 

[middleagecrisis]

Your problem is the hot ethanol fuel bubbling will not lift the float to close the needle and seat. You need to put a return on the system as they did on all carbureted engines 74 and newer. If your using a mechanical pump use the style in the fist picture. With a electric pump and a holley style carb use a return pressure regulator and the style in the second pictures.

I had the same problem. I use to start it with the pump off and turn it on and off until fresh fuel reached the carb. Once I installed the return it fixed the problem. I always install a return on all mechanical pump cars as seen in the first picture. Problem cured.

My race engine never did it with C16 race fuel. Only when putting pump gas to go to car shows.

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My duster is a 75 and has the factory return line on it. I guess the previous owner cappd it off. I do plan on installing an electric fuel pump, bigger lines and a return system when I install the 360. I still don’t understand how the factory return line will keep fuel from boiling in the float bowl.

 

[Big.J.007]

It doesn't.. just keeps the incoming fuel from getting preheated and evaporated. Run ethanol free from Qt or live with it till swapping carbs. It's a fuel soak issue.

My duster is a 75 and has the factory return line on it. I guess the previous owner cappd it off. I do plan on installing an electric fuel pump, bigger lines and a return system when I install the 360. I still don’t understand how the factory return line will keep fuel from boiling in the float bowl.

 

[4spdragtop]

We had percolating issues on our 273 and 1405 Eddy, installed Edelbrock spacer, all good. Even on the 340 that's in there now.

 

[remytherat]

Another thought: blocking the exhaust crossover on the intake drops intake temp a ton, and keeps the carb much, much cooler

 

[mbaird]

So what changed from the Carter AVS /AFB design to the Edelbrocks 1405 design?
Certainly new Mopars back in the day didn’t suffer from this .

 

[middleagecrisis]

It doesn't.. just keeps the incoming fuel from getting preheated and evaporated. Run ethanol free from Qt or live with it till swapping carbs. It's a fuel soak issue.

I think QT ethanol free is the answer for me right now. I’m not having vapor lock issues, I’m having fuel boiling in the bowls. I do plan on going to a return style fuel system in the future. Before I put a bunch of work into the 5/16” fuel line that’s on there now. I’ll try the QT solution and go from there. Thanks everyone!

 

[mbaird]

Another thought: blocking the exhaust crossover on the intake drops intake temp a ton, and keeps the carb much, much cooler

My AVS thunder 800 has a similar problem on my Barracuda. Maybe I will try installing it on my W2 headed 408 in the Swinger to see if it happens on it ? No heat crossover and a Victor single plane . If it persists then I could cross out heat soak….

But the Barracuda only does it if it sits for a few days . Even when I run non-ethanol fuel .

 

[Oldmanmopar]

My duster is a 75 and has the factory return line on it. I guess the previous owner cappd it off. I do plan on installing an electric fuel pump, bigger lines and a return system when I install the 360. I still don’t understand how the factory return line will keep fuel from boiling in the float bowl.

The fresh fuel coming in cools the fuel . But if you have hot bubbles coming in the float will not shut the incoming fuel off. With out a return the fuel is dead ended. The return prevents the push of the hot fuel. Believe me. This only occurs after driving it and then letting it sit for 15 minutes. If you shut it off and immediately restart it it will not flood over. But let it sit and try and start it. That is when it will flood.

One other thing to do that helps to save the carb and headers if leaving the car sit over winter. add top lube or alcohol fuel lube to your fuel. It stops the headers from rusting from the inside and the carb from corroding.

Never run a holley empty. I found after shutting the pump off and running the car out of fuel the primary bowl and all components corroded. The rear bowl with fuel still in it was like new. Just some info I found over the years.

 

[Bewy]

[1] Engine at operating temp, switch off, & look in the t/bores with a flashlight. Look for fuel dripping; you may have to do this for 10 mins to allow for heat soak.
[2] After letting sit 10-15 min, activate acc pump. If you do not get pump shot, driver's side f/bowl is dry.

 

[RustyRatRod]

I recently switched to non ethanol 90 octane in Vixen and I can tell a huge difference. Try it.

 

[middleagecrisis]

[1] Engine at operating temp, switch off, & look in the t/bores with a flashlight. Look for fuel dripping; you may have to do this for 10 mins to allow for heat soak.
[2] After letting sit 10-15 min, activate acc pump. If you do not get pump shot, driver's side f/bowl is dry.

I’ll check on this tomorrow.