Did Anyone Try This?

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73Swinger18

73Swinger18

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Camarillo, CA
I have a '73 Dart with a 318 and mechanical fuel pump and considering using the fuel vent line that comes from the sending unit up to the engine bay as a fuel return line. I would use a filter like NAPA 3054 with a second outlet and hook it directly up to the vent line after cutting off the ball check valve. I would use a vented cap or add a vent to the top of the filler tube like earlier models. I understand the importance of keeping the cannister and having the fuel return enter the tank below the gas level, but would just like to know if anyone has done this before with any success. I am trying to do everything I can to prevent percolation and vapor lock. I will also have a 1/2" phenolic carb spacer, carb heat shield, and insulate all fuel lines. Thank you!
 
Are you saying you will filter the return fuel? Absolutely no need for that. The supply filter is all you need, but the rest is a good idea. I have done it before on other cars and am going to do it on my rat rod build.
 
I thought the OP found a new way to pleasure oneself.
I guess I'll look elsewhere....:D
 
I am trying to do everything I can to prevent percolation and vapor lock. I will also have a 1/2" phenolic carb spacer, carb heat shield, and insulate all fuel lines. Thank you!
Click to expand...
Are percolation and vaporlock, real problems in Camarillo?
A good way to get rid of underhood heat is a big 7-blade fan on a thermostatic fan-clutch, AND fresh cold air to the carb.
The fresh air alone will make a HUGE difference.Undehood air can reach several hundred degrees with headers acting like pretty good radiators, Aluminum heads will also radiate a lot of heat.
The big fan will push a lot of heat underneath and away from the car.
Between those two, I solved all my heat issues. But up here we rarely have temps over 99*F, and only for about a week in summer, Two tops. No other heat-busting ideas were employed.
The bonus of the fresh air was a solid stable,dependable,700rpm with a 230 cam and 14* idle timing; and a 93mph trap speed in the 1/8th. If you are having heat related issues, get fresh air, whatever it takes! Sucking air at 250 plus degrees.......SUX ! Besides, you can't make decent power on that air, and it will cost you at least one grade of gas. This should be important on all SBMs but especially the smaller ones. Carbs do not come calibrated for hot air.
I run the Mopar P4007040 HO-pump, right out of their catalog, no return and all bare steel to the 750DP on an AG with just the 1/4 inch gasket. I used 3/8 steel line from the 3/8 sender, with a large canister EFI filter mounted just ahead of the Passenger side, front spring perch. 125,000 miles, and since 2000, and still going.
Oh Yeah, I have never run anything but 87E10 on the street, AND with a 10.97 starter gear(4-speed)I can drag the engine idle down to 550 rpm, about 3.5 to 4 mph,walking speed, and the car will pull itself around on flat hard pavement. Now that's a solid stable dependable idle!
 
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AJ/FormS said:
Are percolation and vaporlock, real problems in Camarillo?
A good way to get rid of underhood heat is a big 7-blade fan on a thermostatic fan-clutch, AND fresh cold air to the carb.
The fresh air alone will make a HUGE difference.Undehood air can reach several hundred degrees with headers acting like pretty good radiators, Aluminum heads will also radiate a lot of heat.
The big fan will push a lot of heat underneath and away from the car.
Between those two, I solved all my heat issues. But up here we rarely have temps over 99*F, and only for about a week in summer, Two tops. No other heat-busting ideas were employed.
The bonus of the fresh air was a solid stable,dependable,700rpm with a 230 cam and 14* idle timing; and a 93mph trap speed in the 1/8th. If you are having heat related issues, get fresh air, whatever it takes! Sucking air at 250 plus degrees.......SUX ! Besides, you can't make decent power on that air, and it will cost you at least one grade of gas. This should be important on all SBMs but especially the smaller ones. Carbs do not come calibrated for hot air.
I run the Mopar P4007040 HO-pump, right out of their catalog, no return and all bare steel to the 750DP on an AG with just the 1/4 inch gasket. I used 3/8 steel line from the 3/8 sender, with a large canister EFI filter mounted just ahead of the Passenger side, front spring perch. 125,000 miles, and since 2000, and still going.
Oh Yeah, I have never run anything but 87E10 on the street.
Click to expand...
I have a 7 blade with a new thermostatic clutch. It still gets hot under there with those long tube Hedmans. I was joking about just cutting a scoop if all else fails. I do like the look of scoops......
 
I would never tell you to cut a hole in your hood and seal it to the carb. But if you do cut a hole in your hood, seal it to the carb.
My IR gun says that headers idle in the 300 to 500 Degree range right at the flange. My aluminum heads run a tic over 205,and so does the top of my rad. There is no other way for the hot air to escape from under my hood except down. So the 205* plus air from the rad flows over the hot heads and down over the really hot headports, down the hot tubes over the relatively cooler oil filter and P/S box,and out the bottom. I have no idea of the exit temperature, but I bet you could burn marshmallows in a heartbeat! Of course heat rises, so heat is trying to cook the carb. I have a 68 hood with those neat-O metal hood dress-ups. I elevated them with spacers, and cut a bunch of exhaust ports under them, fitting them around the hood bracing. With the car stopped you can really feel the heat coming outta there.
Ram air boxes are available to bring fresh air in from behind the headlights, but they are pricey. I was too broke for that, I'm always too broke. I had a spare factory hood, so out came the jigsaw!
 
73Swinger18 said:
Yeah, EFI with a return
Click to expand...
Untrue. Returnless systems still offer the same benefit; namely that boiling point of the fuel is raised significantly by the fuel system pressure. To the point that multi point efi cars allow the garbage gas we have to deal with now.

If you can't beat them, join them! (Which is why I'm not a Ford or Chevy guy)

Also, if I'm understanding what you've started correctly, you don't want your return below fuel level. Any leak in the system would cause siphoning.
 
AJ/FormS said:
I would never tell you to cut a hole in your hood and seal it to the carb. But if you do cut a hole in your hood, seal it to the carb.
My IR gun says that headers idle in the 300 to 500 Degree range right at the flange. My aluminum heads run a tic over 205,and so does the top of my rad. There is no other way for the hot air to escape from under my hood except down. So the 205* plus air from the rad flows over the hot heads and down over the really hot headports, down the hot tubes over the relatively cooler oil filter and P/S box,and out the bottom. I have no idea of the exit temperature, but I bet you could burn marshmallows in a heartbeat! Of course heat rises, so heat is trying to cook the carb. I have a 68 hood with those neat-O metal hood dress-ups. I elevated them with spacers, and cut a bunch of exhaust ports under them, fitting them around the hood bracing. With the car stopped you can really feel the heat coming outta there.
Ram air boxes are available to bring fresh air in from behind the headlights, but they are pricey. I was too broke for that, I'm always too broke. I had a spare factory hood, so out came the jigsaw!
Click to expand...

this is what i did to get cold air into the engine



1470259101_zpsrrxsk9bt.jpg



what you cant tell from the pictures are the two 90 degree silicone couplers hidden inside the fender
these are pointed forward and slightly up to keep the road debris, kicked up by the wheels from being sucked into the engine
they may or may not also work as a little bit of a ram air intake
 
diymirage said:
this is what i did to get cold air into the engine



View attachment 1715011172


what you cant tell from the pictures are the two 90 degree silicone couplers hidden inside the fender
these are pointed forward and slightly up to keep the road debris, kicked up by the wheels from being sucked into the engine
they may or may not also work as a little bit of a ram air intake
Click to expand...
think I`d check my air filter often !
 
diymirage said:
this is what i did to get cold air into the engine



View attachment 1715011172


what you cant tell from the pictures are the two 90 degree silicone couplers hidden inside the fender
these are pointed forward and slightly up to keep the road debris, kicked up by the wheels from being sucked into the engine
they may or may not also work as a little bit of a ram air intake
Click to expand...


A pic of my cold air slightly pressurized at speed from the cowl..

Airbox1.JPG


Airbox2.JPG
 
hey 73
I live in Moorpark 15 minutes from you and never had an issue with vapor lock. would I be wrong to suggest an electric fuel pump ? I have a 360/380 magnum crate motor in my 68 barracuda and those motors do not accept a mechanical pump so I have never tried one.
 
terry said:
hey 73
I live in Moorpark 15 minutes from you and never had an issue with vapor lock. would I be wrong to suggest an electric fuel pump ? I have a 360/380 magnum crate motor in my 68 barracuda and those motors do not accept a mechanical pump so I have never tried one.
Click to expand...
Hey neighbor! A lot of the heat under my hood comes from long tube headers and aluminum intake. I installed this return line along with a Holley aluminum carb heat shield and am no longer experiencing the stumble at idle when hot or long start times after the car has sat for 20+ minutes after driving. The return lines flows real well and keeps the fuel cool in the lines now. I am using a Stant locking fuel cap that I removed the spring relief out of so it breathes with no pressure build up.
 
73Swinger18 said:
Hey neighbor! A lot of the heat under my hood comes from long tube headers and aluminum intake. I installed this return line along with a Holley aluminum carb heat shield and am no longer experiencing the stumble at idle when hot or long start times after the car has sat for 20+ minutes after driving. The return lines flows real well and keeps the fuel cool in the lines now. I am using a Stant locking fuel cap that I removed the spring relief out of so it breathes with no pressure build up.
Click to expand...

hi 73
good to hear. I did forget to say I have a 6 pack scoop sealed to my carb.
thanks
terry
 
73Swinger18 said:
I have a '73 Dart with a 318 and mechanical fuel pump and considering using the fuel vent line that comes from the sending unit up to the engine bay as a fuel return line. I would use a filter like NAPA 3054 with a second outlet and hook it directly up to the vent line after cutting off the ball check valve. I would use a vented cap or add a vent to the top of the filler tube like earlier models. I understand the importance of keeping the cannister and having the fuel return enter the tank below the gas level, but would just like to know if anyone has done this before with any success. I am trying to do everything I can to prevent percolation and vapor lock. I will also have a 1/2" phenolic carb spacer, carb heat shield, and insulate all fuel lines. Thank you!
Click to expand...
After reading all these posts about most everything but ur question: I use a 3/8" pick up as a return line, w/ the sock cut off. The return should be below the fuel level so as not to airorate (sp) the fuel. Just be sure it doesn`t cause any turbulence w/ the pick up. You can find this info about return systems if u look.
 
famous bob said:
After reading all these posts about most everything but ur question: I use a 3/8" pick up as a return line, w/ the sock cut off. The return should be below the fuel level so as not to airorate (sp) the fuel. Just be sure it doesn`t cause any turbulence w/ the pick up. You can find this info about return systems if u look.
Click to expand...

I used a short length of submersible fuel line to add a second piece of bent 3/8" aluminum tubing to direct the fuel and allow the installation of the sending unit etc into the tank.
 
wireweld said:
What did you use for tubes out of the cowl and how did you attach to the cowl?
Click to expand...
I used common hardware store dryer ducting and some sheet metal ducting flanges. The kind used to attach the ducting to a flat surface. I cut the holes out using a 4" hole saw.
 
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