Underhood fuel line routing help

[767Jockey]

Well, the problems continue, my brand new block arrived, was machined, and we found that it's no good. Right now I am "negotiating" with the supplier for a new one. Yeah, I know that I shouldn't have to "negotiate" for a damned thing on a brand new block that turns out to have porosity problems that are only evident after machining...it's a long story, I'll let everything play out before I say anything.

Anyway, the project is almost dead in the water while I wait for the block supplier to decide what he's going to do. My thoughts turn to the fuel line. I am having Nick Acton (Mickmate) build me a custom S/C style fuel tank. I'm running a Mallory 250GPH electric pump with a 1/2" fuel line. I have no mechanical pump, there will be a fuel pump block off plate there. I'll have the pump eccentric installed in case I want to go mechanical somewhere down the road. I have a large Holley !/2" in, 1/2" out regulator. I am figuring that I will put the regulator down in the area where the fuel pump normally goes. Maybe I can have a bracket fabricated for it that uses the bolts for the block off plate to mount the regulator securely, with a short length of steel braided line that bridges the hard line on the frame to the regulator to allow for engine movement. For appearance sake I'd like to run hard line from the regulator to the 1X4 fuel log. How is this line normally routed? Anyone have pictures of the stock line routing? What do you guys think of this plan - any ideas are always welcome and appreciated.
Doug

[Rick Parker]

Instead of hardline which will absorb a lot of heat I would suggest using a Black cloth covered line such as what is available from Earls. It looks good and won't transfer a lot of heat into the fuel.

Rick

[Tommy]

Regarding your plans for the fuel pressure regulator - I recommend a regulator with one input and two outputs (one to the carb and the other back to the fuel tank). They are much easier on the fuel pump. If you do that, you may want the regulator just after the pump so you don't have to run the return line so far.

[767Jockey]

Originally Posted by Tommy

Regarding your plans for the fuel pressure regulator - I recommend a regulator with one input and two outputs (one to the carb and the other back to the fuel tank). They are much easier on the fuel pump. If you do that, you may want the regulator just after the pump so you don't have to run the return line so far.

Actually the Mallory 250 GPH pump has a built in return, so I only need to run the return line from the pump back to the tank, and use a deadhead regulator.

[Cobrabill]

Originally Posted by 767Jockey

Actually the Mallory 250 GPH pump has a built in return, so I only need to run the return line from the pump back to the tank, and use a deadhead regulator.

That system passes up a great opportunity to cool the fuel,which in any equation is a great thing.

[767Jockey]

Originally Posted by Cobrabill

That system passes up a great opportunity to cool the fuel,which in any equation is a great thing.

How does a longer return line equate to cooler fuel?

[Cobrabill]

O.K.If this was my car,i plug the second port on the pump,run the line to the back of the fuel rail.Then i'd run the line out the front of the fuel rail down to the reg mounted in place of the mech. fuel pump and back to the tank.

My car is plumbed a little different.The fuel pump is out back(duh),the inlet is up front.This comes as a result of a previous plumbing arrangement(mechanical pump in the loop),then i came to my senses and trashed the mechanical.The reg is mounted at the rear of the fuel log.The return line (4AN)then is metered with a Holley carb jet and runs back to the tank.

This does two things:
1) relieves the deadhead situation on the pump.Previously discussed.
2)It does deliver cooler fuel to the carb.I know the ambient temp of the gas tank isn't exactly arctic-like but it definately is cooler than the fuel log sitting above the engine.

I know out on the Island you don't experience heat like i do,but i tend to take fuel systems one better as i have a turbo car that there is no margin for error on.

[767Jockey]

OK, fuel moving keeps it cooler instead of sitting and getting compressed against the deadhead regulator. I get it now. It takes me a while to catch on. Getting older sucks, I never thought it would happen to me.

[CHANMADD]

I run a Holley Blue electric pump.I have the pump at the back close to the tank and actually mounted the regulator on the block where the stock pump goes. It is dead headed and I have no problems with it at all. I will say that I am prbably going to go back to a mechanical pump for safety reasons and also it is not as noisy.
john

[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

[CHANMADD]

I am 100% with Jerry here! I have always said that the OEM ,read ,factories pay 100's of thousands to highly qualified engineers to come up with the best and safest methods of doing things. All the other geniuses who own cars always come up with beter ways of wasting money on unnecassary and often times unsafe "bling". Just like all the threads about faulty aftermarket ignitions and the like......beats me!!!!...............KISS!!!
john

[767Jockey]

I've been told by more than a few highly respected engine guru's that other than perhaps RobbMc's mechanical pump, none of the other mechanical pumps will have the capacity to feed my engine should I decide to take it to the track, which I hope to do. I feel better with the big electric pump back there, KNOWING that it'll work, than with a marginally sized mechanical HOPING that it'll work. Every engine guy I spoke with, and every article I referenced, speced a 1/2" fuel line and a higher pump flow rate than either of the mechanical pumps mentioned in the post above. I don't have the numbers handy in front of me, that was a while ago. However, I'll stick with what I've got, I KNOW it'll work. This "genius" doesn't have all the answers, but I know enough to go to QUALIFIED experts to learn what I don't know. They said to set it up the way I have it. Last I knew, the factory didn't produce a 640+HP car, and certainly not one with a mechanical fuel pump. Required fuel flow and delivery is a function of the HP that it feeds.

[767Jockey]

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,
You have a PM.

[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?

[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?

[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.

[Cobrabill]

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

[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 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.