Fuel feed line opinions needed

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MidnightSwinger

MidnightSwinger

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318 Aspen Wagon:

I live in Vegas and daily drive my Wagon. 318 factory 4bbl with eddy 600 on top. I of course have all the fun problems with that combo and 100°+ temps and stop and go driving. Vapor lock, fuel percolation, the fun stuff.

My question is this: What it the best setup for the feed line? The line that goes from the pump to the filter/carburator.

I bought the car with a metal line that runs in front of the engine, and attaches to the filter and fuel pump using fuel hose. I don't believe that this is the factory feed line, and I believe it may be causing some of my issues.

Should I look for the correct feed line from a stock LA or could I build something better? Any ideas and input about fuel lines and insulating them is very much appreciated.

I am running the stock mechanical fuel pump, and would like to stay away from an electric fuel pump if possible.

Thanks

I attached a crappy picture of the current feed line. It almost looks stock, but it doesn't thread into the fuel pump, it uses rubber fuel hose.

IMG_20180412_191800_152.jpg
 
looks pretty stock to me
i would add a return line to it, to keep the fuel moving about and keep it from boiling
 
You are boiling the fuel with the line ran over the heater hoses.
The fuel line goes under it, and the heater hose bracket that supports the hoses up is missing on your engine.
 
sireland67 said:
You are boiling the fuel with the line ran over the heater hoses.
The fuel line goes under it, and the heater hose bracket that supports the hoses up is missing on your engine.
Click to expand...

I noticed that, this picture is when I first got the car, I had since run the fuel line away from the heater hoses.
 
sireland67 said:
You are boiling the fuel with the line ran over the heater hoses.
The fuel line goes under it, and the heater hose bracket that supports the hoses up is missing on your engine.
Click to expand...

Likely not. The heater hoses are likely colder than the block. The exhaust is one big thing that causes fuel boil

Best thing I did for the 67 before I went EFI is a carb spacer/ insulator, block the intake crossovers, build a return setup (Use a Wix 33040 / 41 series filter with a built in orifice) and rear mount electric pump

Do NOT use the carbon canister (evap vent system) tube for a return tube. On the 76/ earlier cars that is the tank vent. Don't know about the Aspens
 
67Dart273 said:
Likely not. The heater hoses are likely colder than the block. The exhaust is one big thing that causes fuel boil

Best thing I did for the 67 before I went EFI is a carb spacer/ insulator, block the intake crossovers, build a return setup (Use a Wix 33040 / 41 series filter with a built in orifice) and rear mount electric pump

Do NOT use the carbon canister (evap vent system) tube for a return tube. On the 76/ earlier cars that is the tank vent. Don't know about the Aspens
Click to expand...

Already tried a spacer with decent results, just received the .333" insulator/gasket from edelbrock to try out.

I'm considering a return line, but would like to avoid the electric fuel pump if possible. If that is the final piece so be it, but I think ill try everything else first.

Carbon canister is long gone and the line kinked by the PO. I almost considered a cool can, but how often would I be putting ice into it? What about insulating the metal lines?

KISS is the name of the game here, hence not wanting the electric fuel pump. I bought the wagon for 1k so I'm trying to not sink too much $$ into it.
 
The cooling system can be at over 200*.
Your underhood air temp can be several hundred degrees. Your engine is sucking all that hot air right down the hatch.
Put an IR gun on your steel line. I bet it's over 100*F,lol.
I think gasoline starts to boil at 95*F, at atmospheric pressure.
Every time your float valve opens, the gas in the line goes close to atmospheric pressure, even if for only milliseconds. But the gas dropping into the carb is already at way over 100*F, so when it scoots thru the valve..... into atmospheric pressure, it is apt to boil right then.
You can pull the top of most Carter 2bbl carbs, and run the engine with them off..... And you can watch the gas boil as it exits the float valves; I have done this and seen it.
95*F.
Your fuel system from pump to valve and carb bowl needs to stay under this.
How is that possible on a 100* day?
It's not.
But there are over 200 compounds in gasoline and only the lightest boil at 95, some don't until nearly 400*F.
The questions are, where is the boiling gas going?, and how can I keep my carburetor under 95* on a 100* day with 200/250Plus degrees air being blasted at it by the fan/
I don't know, but I can tell you what I did;
Step 1; I cut a hole in my hood, and connected the top of the carb to the underside of the hood. Now,on a100* day, the carb gets 100* air. Not 200,not 300,nor even 350* air.
Step 2; I redirected the air coming thru the rad downwards
Step 3; I installed a 3/8 pressed paper gasket under the carb.
Step 4; I installed a 3/8 steel line from the tank to the 7psi pump,then directly to the carb,without filter, or rubber parts; and I routed that line away from hot engine parts.
Step 5; I put a bigazz EFI filter at the back in the airstream.
Step 6; I run 87E10.... with maximum advertised 10%alcohol in it.
Step 7; I run a DP carb, and a sq-top SuperCoil
Now how this works, I think, is like this;
The bigger steel line acts like a radiator, putting the heat into the airstream. The 7psi pump and one piece line from pump to carb maintains the fuel at pressure all the way to the float valves. The float bowls are cooled by the main body, which, as long as the engine is running, is being cooled by pressure change that happens in the venturis, which I'm hoping is aided by the alcohol in the fuel. The paper gasket prevents the heat from coming up from the AirGap intake, and spoiling the venturi cooling.And the air coming down from the top of the hood is at ambient temp.
>I have aluminum heads and naked TTI headers,and my minimum coolant temp is 205*F. It's like blast furnace under there.And finally, I ventilated the hood so that when I turn the car off, the hot air escapes upwards, "pulling" fresh cooler ambient air up from the bottom, by pressure differential; hi pressure air always moves to a low pressure area.
The advantage of the DP carb is that if the car sits for a week or three, a full length stab on the pedal is usually all it takes to fire her up, on the syrup that might be all that's left over in the half empty bowls. And the Accell Bad-Boy coil will light anything.

>I have trouble with carburetor-icing on cold days. lol.
 
Last edited:
AJ/FormS said:
The cooling system can be at over 200*.
Your underhood air temp can be several hundred degrees. Your engine is sucking all that hot air right down the hatch.
Put an IR gun on your steel line. I bet it's over 100*F,lol.
I think gasoline starts to boil at 95*F, at atmospheric pressure.
Every time your float valve opens, the gas in the line goes close to atmospheric pressure, even if for only milliseconds. But the gas dropping into the carb is already at way over 100*F, so when it scoots thru the valve..... into atmospheric pressure, it is apt to boil right then.
You can pull the top of most Carter 2bbl carbs, and run the engine with them off..... And you can watch the gas boil as it exits the float valves; I have done this and seen it.
95*F.
Your fuel system from pump to valve and carb bowl needs to stay under this.
How is that possible on a 100* day?
It's not.
But there are over 200 compounds in gasoline and only the lightest boil at 95, some don't until nearly 400*F.
The questions are, where is the boiling gas going?, and how can I keep my carburetor under 95* on a 100* day with 200/250Plus degrees air being blasted at it by the fan/
I don't know, but I can tell you what I did;
Step 1; I cut a hole in my hood, and connected the top of the carb to the underside of the hood. Now,on a100* day, the carb gets 100* air. Not 200,not 300,nor even 350* air.
Step 2; I redirected the air coming thru the rad downwards
Step 3; I installed a 3/8 pressed paper gasket under the carb.
Step 4; I installed a 3/8 steel line from the tank to the 7psi pump,then directly to the carb,without filter, or rubber parts; and I routed that line away from hot engine parts.
Step 5; I put a bigazz EFI filter at the back in the airstream.
Step 6; I run 87E10.... with maximum advertised 10%alcohol in it.
Step 7; I run a DP carb, and a sq-top SuperCoil
Now how this works, I think, is like this;
The bigger steel line acts like a radiator, putting the heat into the airstream. The 7psi pump and one piece line from pump to carb maintains the fuel at pressure all the way to the float valves. The float bowls are cooled by the main body, which, as long as the engine is running, is being cooled by pressure change that happens in the venturis, which I'm hoping is aided by the alcohol in the fuel. The paper gasket prevents the heat from coming up from the AirGap intake, and spoiling the venturi cooling.And the air coming down from the top of the hood is at ambient temp.
>I have aluminum heads and naked TTI headers,and my minimum coolant temp is 205*F. It's like blast furnace under there.And finally, I ventilated the hood so that when I turn the car off, the hot air escapes upwards, "pulling" fresh cooler ambient air up from the bottom, by pressure differential; hi pressure air always moves to a low pressure area.
The advantage of the DP carb is that if the car sits for a week or three, a full length stab on the pedal is usually all it takes to fire her up, on the syrup that might be all that's left over in the half empty bowls. And the Accell Bad-Boy coil will light anything.

>I have trouble with carburetor-icing on cold days. lol.
Click to expand...

I enjoyed reading your post. We are definitely thinking similar. The F bodies come with a cool air intake of sorts. Pulls air from in front of the radiator. I thought about venting, maybe cut some holes in the hood. I was just thinking about the 3/8" fuel line upgrade today, same thought as you. Can you show me some pictures of how you diverted the rad air? That sounds like a good idea.

Thanks
 
I think that the mechanical fuel pump adds a lot of heat to the fuel. I think you're better off switching to an electric pump and insulating the fuel lines around the engine. See Vapor Lock.

 
fjr said:
I think that the mechanical fuel pump adds a lot of heat to the fuel. I think you're better off switching to an electric pump and insulating the fuel lines around the engine. See Vapor Lock.

Click to expand...


I read that link recently and its one of my reference points. Im trying to stay away from the electric fuel pump due to cost/reliability concerns. Also my issues are never that severe, hard starting and bogging with more than 1/2 throttle. Mostly just annoying.

Ill start with blocking the heat crossover during summer months, insulating the lines, and look into controlling underhood temps. I'm thinking header wrap, hood vents and maybe diverting the radiator air away from the carb/intake as mentioned by @AJ/FormS above. Anything I can do cheap/free ill try, and report my results.
 
You can buy or build a large aluminum plate to install under your 4bbl carb.It sticks forward about 5 or 6 inches. You can bend that up or attach stuff to it.
Make sure all your rubber lines on the supply side are in good shape, and if you have gear clamps on them, install two per joint with screw heads at 180* from eachother; and I like to point the screw slots in opposite directions whenever I can. Pay particular attention to the jumper at the sender. It is above the liquid-line in the tank, and will not always leak if the joint is not secure. But the pump will suck air there if it can; and especially so if the tank-vent is not properly working. If the air leak is not severe, the pump will pull it up and push it into the bowl, and from there to atmosphere. As the leak gets worse, eventually the pump would pump nothing but air. Of course your engine would quit running before this happens,lol.
Make sure your fresh air system is working properly, especially the mixing valve that tries to maintain a specific inlet air temperature; up here at 85*F, IIRC. You know; that heat stove/thermactor thingy. It has it's controller inside the air filter housing.The carb is calibrated to run with that temperature. If you defeat it so that the carb gets only air at ambient temp, you will have trouble when the temp drops, later in the year.
 
Last edited:
AJ/FormS said:
You can buy or build a large aluminum plate to install under your 4bbl carb.It sticks forward about 5 or 6 inches. You can bend that up or attach stuff to it.
Make sure all your rubber lines on the supply side are in good shape, and if you have gear clamps on them, install two per joint with screw heads at 180* from eachother; and I like to point the screw slots in opposite directions whenever I can. Pay particular attention to the jumper at the sender. It is above the liquid-line in the tank, and will not always leak if the joint is not secure. But the pump will suck air there if it can; and especially so if the tank-vent is not properly working. If the air leak is not severe, the pump will pull it up and push it into the bowl, and from there to atmosphere. As the leak gets worse, eventually the pump would pump nothing but air. Of course your engine would quit running before this happens,lol.
Make sure your fresh air system is working properly, especially the mixing valve that tries to maintain a specific inlet air temperature; up here at 85*F, IIRC. You know; that heat stove/thermactor thingy. It has it's controller inside the air filter housing.The carb is calibrated to run with that temperature. If you defeat it so that the carb gets only air at ambient temp, you will have trouble when the temp drops, later in the year.
Click to expand...

I'm in the process now of replacing all the rubber on the supply side, going to use high pressure FI hose for the rigidity and resistance to alcohol. Ill be extra diligent at the sending unit.

The thermostatic air control was disabled by the PO; probably when he installed the headers. Its not needed here 10 months out of the year anyway. Also Ive already gone through winter here without it, and it LOVES cold starts....weirdest mopar small block I've ever had. Runs amazing under 80° every other SBM I've ever dealt with was cold blooded. Still has lean burn controlling ignition, but an edelbrock 600 instead of the LB carb.
 
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