Underhood fuel line routing help

[767Jockey]

Originally Posted by Cobrabill

John,what safety issue?Also,how can you hear the pump with sidepipes?

Bill, I was kind of thinking the same thing with regard to noise. I am going to have 490+ inches of 10.5:1 compression FE bellowing through a 3" core muffler about 30" from my ear. I haven't driven the car yet, but I would truly be shocked if I could hear the electric fuel pump running. I have a crash switch on the pump to shut it off if it senses impact, which obviously would eventually shut the engine as well. I don't see a safety issue either. I have tried my very best to do everything on this car the RIGHT way. I can not think of a single corner that I have cut in building this car.

[CHANMADD]

CobraBill, To be honest I can only hear the pump at idle.
The safety thing ...for me is that no matter what with a mechanical pump when the motor shuts down so does the gas...for sure. Even if I spin the car and lock it up and kill the motor the gas stops pumping. i did race my car a 406 cu and never had fuel starvation with the mechanical pump and believe me I rev the hell out of my motor.
just my 02c
john

[Cobrabill]

Originally Posted by Jerry Clayton

Doug

the next time you are at work, you do the walk a round---notice the plumbing used---the braided stuff was WW2----toss the electric pump, and regulator, put on a holley or edelbrock mechanical pump, no regulator and hard line to the carb. Use a short rubber hose from hard line along or inside your frame to the fuel pump inlet on the engine.

the electric pumps are noisy, and create other problems and risk areas---do it like was on oem cars running carbs in the 60s and 70s---make sure your tank is vented

Jerry,really,REALLY bad advice.If you advocate rubber line over braided,you really need to sell your Cobra and drive a VW Beetle.

Electric pumps create NO bad situations.Or risks.Every car in every dealership today has an electric fuel pump.Noisy?You're concerned with a noisy fuel pump on a car that can be heard from two blocks away?

[Cobrabill]

Originally Posted by CHANMADD

CobraBill, To be honest I can only hear the pump at idle.
The safety thing ...for me is that no matter what with a mechanical pump when the motor shuts down so does the gas...for sure. Even if I spin the car and lock it up and kill the motor the gas stops pumping. i did race my car a 406 cu and never had fuel starvation with the mechanical pump and believe me I rev the hell out of my motor.
just my 02c
john

No offense John,but if your 406 wasn't running out of fuel with just a mechanical pump,then it wasn't much of a motor.

A mechanical pump(by itself) will NOT feed my Side-Oiler.

As i posted earlier,every car today has a electric pump.

[RICK LAKE]

767Jockey Doug, the setup you have will be fine. Like others here on the forum a return line will extend the life of your fuel pump or pumps. From racing I can tell you that running an FI system with a return line from the front of the car does raise the fuel temp. Some of the heat comes from the track surface in the daytime, some comes from the resistance of the fuel lines and the pressure pushing the fuel through the system. With the amount of heat under a cobra hood, any line that can help insolate the heat from the fuel would be a help. I think the engineers at wherever added the turkey pan around the carb for a heat insolator because of high fuel temps and vaporlock and to add cooler air from outside the car. Your supply line size is fine. Cooler the gas the less problem of vapor lock you will have. I do open the hood after running to help remove added heat from the engine compartment. I would reccommend this to any one who has gone on a long cruise and stops for 10-15 minutes. This also helps stop the fuel in the carb bowls from boiling and the fuel pressure in the lines from increasing and pushing the floats open. This will cause a washing of the cylinders, black smoke and hard startup. Not good. Rick L.

[Jerry Clayton]

CobraBill----braided line is rubber---

Problems with braided line----cutting and assembling ----multitude of fittings required, usually incompatible fittings will find there way into the install, inproper lengths and clocking of fittings used, wrong flare types used, put together dirty,

they are WW2 era hoses and may not be conpatible with todays fuels

They are still RUBBER hoses and probably made out of trees


Fuel pump safety switches----probably won't activate if you don't hit straight on--hitting a wall sideways or backwards maybe won't shut off
sometimes, it isn't an issue of a crash that you need the pump to shut off, I have seen many cars burn because of a fuel leak from teflon tape usage and a bit gets in the needle/seat causing a flood situation, a backfire ignites the fuel and the owner gets out trys to blow off the flames while his 200 gph pump continues to pump and noone else knows where the switch is.

If any of you guys have the balls to hold one of these cars wide open enough to use more fuel than a mechanical pump can pump---NASA is taking applications

For Doug----if your car is going to truly be as loud as you say---pay attention to the numbers your FAA examiner says on your physical, because someday you'll need to remember them to get your 1st class.

Jerry

[Cobrabill]

Originally Posted by Jerry Clayton

1)CobraBill----braided line is rubber---

2)Problems with braided line----cutting and assembling ----multitude of fittings required, usually incompatible fittings will find there way into the install, inproper lengths and clocking of fittings used, wrong flare types used, put together dirty,

3)they are WW2 era hoses and may not be conpatible with todays fuels

4)They are still RUBBER hoses and probably made out of trees


5)Fuel pump safety switches----probably won't activate if you don't hit straight on--hitting a wall sideways or backwards maybe won't shut off
sometimes, it isn't an issue of a crash that you need the pump to shut off, I have seen many cars burn because of a fuel leak from teflon tape usage and a bit gets in the needle/seat causing a flood situation, a backfire ignites the fuel and the owner gets out trys to blow off the flames while his 200 gph pump continues to pump and noone else knows where the switch is.

6)If any of you guys have the balls to hold one of these cars wide open enough to use more fuel than a mechanical pump can pump---NASA is taking applications

For Doug----if your car is going to truly be as loud as you say---pay attention to the numbers your FAA examiner says on your physical, because someday you'll need to remember them to get your 1st class.

Jerry

1)O.K.-thanks for the clarification.
2)Never had any problems with fittings at any time other than 20 AN fittings.I guess this comes from knowing what your doing.
3)ANY AN line on the shelf today is comapatible with any fuel with the POSSIBLE exception of staight ethanol/methanol.I also never had any problem with the fuel line except making the mistake of using a piece of line i had sitting on the shelf in a 60 PSI application
4)Probably?Not likely.
5)All cars today have electric fuel pumps.But according to you,we should see fireballs at every accident.We don't.Telfon tape has NEVER caused a problem with any fuel system, anywhere on the planet.Idiots USING teflon tape might have though.
Ever hear of a battery switch?

And there's that "probably" word again.To me that means you just don't know.

6)Why else would you own one of these cars?Full throttle runs to 7K rpm thru 3rd gear(by the time i get into 4th,i start running out of road)are common.

There are plenty of motors that REQUIRE an electric pump.I have a inline 6 cylinder(189 CI)that requires an electric pump and a 1/2 inch feed line.Also,a mechanical will not feed a 500 inch motor turning 5K & up.

[Jerry Clayton]

CobraBill

7k in 3rd gear???? how about the Nascar 9k + until the next yellow--

500 inch 5k---we have 500 inch turning 10400( but it does have a electric pump) it also doesn't have anyway to drive a mech pump

The present day cars use electric pumps for the computer control of fuel system not the volume of fuel--they are also very complicated and are inside the tank so if theres a leak so what.

Electric pumps fail more often than mech pumps

Remember that before the internal combustion engines, the fuel was supplied by some one with a shovel----oh, by the way---don't you work for the rail road?????

Doug works for an airline and there the fuel pumps are mechanical--except for electric pumps that transfer fuel source or in case of fuel balance with aux tanks or engine failure

[Cobra #3170]

Originally Posted by Jerry Clayton

Doug

the next time you are at work, you do the walk a round---notice the plumbing used---the braided stuff was WW2----toss the electric pump, and regulator, put on a holley or edelbrock mechanical pump, no regulator and hard line to the carb. Use a short rubber hose from hard line along or inside your frame to the fuel pump inlet on the engine.

the electric pumps are noisy, and create other problems and risk areas---do it like was on oem cars running carbs in the 60s and 70s---make sure your tank is vented

I agree, a 640 hp FE (assuming you can make that much as installed in the chassis) with a terrible BSFC as is common with most FE's would require about 53 gallons of fuel per hour or .88 gallons per minute. I would think an HP mechanical pump with 3/8" line could handle that easily. NASCAR engines used engine mounted mechanical pumps a few years ago at HP levels above 800 so why wouldn't a mechanical pump work on a 640 hp engine?

[Cobrabill]

Originally Posted by Jerry Clayton

CobraBill

1)7k in 3rd gear???? how about the Nascar 9k + until the next yellow--

2)500 inch 5k---we have 500 inch turning 10400( but it does have a electric pump) it also doesn't have anyway to drive a mech pump

3)The present day cars use electric pumps for the computer control of fuel system not the volume of fuel--they are also very complicated and are inside the tank so if theres a leak so what.

4)Electric pumps fail more often than mech pumps

5)Remember that before the internal combustion engines, the fuel was supplied by some one with a shovel----oh, by the way---don't you work for the rail road?????

Doug works for an airline and there the fuel pumps are mechanical--except for electric pumps that transfer fuel source or in case of fuel balance with aux tanks or engine failure

1)THere aren't any "yellows" on the street.And if you do see a yellow at 9K,this whole topic just became moot.
2)And if it did,you'd still be using an electric.
3)Very complicated?3 wire plug,loosen two hose clamps,two bolts and it's in my hands.
I have seen electric pumps stop working,but have never seen one leak.They are inside tanks these days because they use the fuel to cool them-not in case of leaks.

4) my experience says, the difference in failure rate,isn't worth discussing.
5)I'm not THAT old.

[RICK LAKE]

I don't know where some of this info is coming from??
To start with you can get a mechanical fuel pump with a 200 gph for GM motors This bolts to the block and runs off the eccentric cam. This will handle any 500+ cubic inch with the correct fuel line size. I do like an electric fuel pump over a mechanical one because of pulsing that happens. The fuel pressure is more steady with electric rotary fuel pump.
90% of the time when an electric fuel pump fails is because of either bad fuel, running the gas tank on empty if the fuel pump is inside the gas tank, the pump needs the gas to help cool the pump, this extend the life on any in the tank pump. Not changing the filters every 15k miles or poor contacts. I have seen the screen in the tank full of dirt and collapes. No ideas where it came from. Going to a gas station that doesn't change the filters at the pump also cause failures. I have an electric pump with 122,000 miles on it and it still work fine. I have had mechanical pumps on SBC motors and had new one go bad a 20K miles and one live to 144K miles. The diaphragm wears out over time and the gas leaks from the little hole in the top of the pump. This is a case of being lucky or not. Both can live for 100K without failures.
Braided SS line come with a couple of different liners in it. It depends on what fluid you are running through them. Are the lines a pain to make, a little but if done right, no failures. Measure twice and cut once, most people ball park it and leave bends, pinches, rubbing spots, no mounting clamps for the line, long runs to a vibrating source like the motor. These all cause failures. The liners come in a couple of materials, Rubber, synthetic rubber, nylon, teflon, and CPE. You have to use the correct hose for the correct application.
Fuel pump kill switches, they also depend on how they are setup to work. Some switches work with a roll over, some work off a "g" force decellerometer. to cut off the fuel pump. The side effect of this is even if the fuel pump stops working you can have up to 60 psi of pressure in the lines. Line breaks and you have a line with quart of fuel to blow all over the place and light up. If you are using teflon tape on lines, first off there is a tape for fuels and oils only, it's not WHITE, Pink or Yellow. One doesn't work with all applications. If there is teflon pieces in the carb bowls, someone used the wrong stuff or too much was rapped around the threads. There is also a boiler cement that works best to pervent fuel or brake fluid leaks. When couplers are torque to the correct spec, there should be no failures or leaks. At this time this is the best info I have on a couple of the questions. Rick L.

[Jerry Clayton]

on our fe engines for street type cars we use edelbrock performer rpm 110 gph, 6 valve, 3/8 npt x an-8 fittings---no regulator needed---depending on the customer I run either a 3/8 or 1/2 stainless hardline with .035 wall, a short piece of modern high pressure fuel hose between hardline and engine pump and a 1/2 stainless hard line to the carb fuel log---maybe after the drags tomorrow I can get a couple of pics

In my car as I finish it-----it will have electric hi output pump to supply fuel injection system--it will be a simple mounted system with a regulator at the fuel rails and the return line from the regulator returning to the tank----

However, if I get around to getting it more like I want it it will have a Waterman cable drive mechanical pump.

[767Jockey]

Originally Posted by Jerry Clayton

For Doug----if your car is going to truly be as loud as you say---pay attention to the numbers your FAA examiner says on your physical, because someday you'll need to remember them to get your 1st class.

Jerry

Jerry,
I haven't driven the car yet, but I don't expect it will be THAT loud! I'm sure that it'll be loud enough that the hum of the electric pump will not be heard, and even if it is, I don't mind. I remember back in the 70's I had a '68 Nova SS with a wild small block Chevy in it, and in the trunk I had a pair of electric fuel pumps. I don't remember what make they were, but they ran in sort of pulsing burps. All day long in the car you'd hear.....brrrrrrrt, brrrrrt, brrrrt.....on and on. If that didn't drive me crazy, Nothing will!