[old66tiger]

I am getting ready to pull the trigger on a new fuel system for my GTO. First off, let me tell you that when I make mods to the car, I like to try to do it once and only once. Can't afford to keep on throwing money at the car over and over. My car is a 66 GTO convertible with a 455 and a custom built Q-Jet (in the process) which is replacing my tri-power. Anyway, the car see's no track time, just some serious rip and get street pounding.

Anyway, I will be sending the tank to the radiator shop to get a 1/2" bung installed at the bottom of the tank, one at the top of the tank and a new larger vent. From the back of the car, I was going to run 1/2" flexible line from the tank to the frame section located right before the rear wheel and then convert to 1/2" stainless tubing (0.028" wall tubing). Reason for the conversion to tubing is that I need to run the tubing through the frame (front of the car) along side of the 5/16" factory fuel line and the area where the fuel line pass THROUGH the frame looks to be too small to accommodate a 1/2" hose along with the 5/16" tubing. I plan to use the 5/16" tubing for either a bypass system like Cliff uses or vapor return line for a mechanical system.

So, here are my choices:

1. Comp 140 electric back at the tank with a RobbMc pre-filter. Mount a RobbMc fuel pressure regulator at the motor and right before the regulator, insert a T in the line to recirculate some of the fuel back to the tank (Cliff's design). Run a RobbMc post filter.

2. RobbMc 1100 series mechanical pump up front with a RobbMc regulator. Run a RobbMc pre and post filter and install a vapor return fitting on the regulator to send back a small portion of the fuel to the tank to reduce possibility of vapor lock.

Both options are a big investment for me and without any real experience with either option, I am in a deadlock situation.

Electric pros and cons:
+ when plumbed properly, constant supply of cool fuel to the carb
+ remove clutter at the front of the motor except for the regulator.
- Not as reliable??? Reports of people losing an electric pump without much warning.
- electric draw on the alternator - even as small as it is, there is still drain on the system.

Mechanical pros and cons:
+ Very reliable - not too many reports of the pump just dying.
+ the 1100 pump can be used with an external regulator, improving delivery and the ability to run lower pressures to keep from over driving the carb seat.
+/- Can recirculate a small portion of fuel like the electric however the potential exists for heating the fuel
- lots of equipment to fit in a small space by the motor. regulator will see some heat from the motor.
- reports of some that run out of fuel on the top end.
+ Excellent customer support

Am I over thinking this to the max??? Just want a reliable car that I can get in, hit the key and not have to worry about carrying around spare parts with me.

Opinions welcomed. Thanks...

[67ramair4]

Why do you need so much fuel if it's not seeing the strip? 3/8" line from the tank to Carter electric pump to a Carter mechanical pump up front. I've used this for over 30 years without any fuel starvation issues. Yes, it did see the strip; 12.7 ET's (back in the day of good gasoline).

Just wondering,
Jake

Originally Posted by old66tiger

I am getting ready to pull the trigger on a new fuel system for my GTO. First off, let me tell you that when I make mods to the car, I like to try to do it once and only once. Can't afford to keep on throwing money at the car over and over. My car is a 66 GTO convertible with a 455 and a custom built Q-Jet (in the process) which is replacing my tri-power. Anyway, the car see's no track time, just some serious rip and get street pounding.

Anyway, I will be sending the tank to the radiator shop to get a 1/2" bung installed at the bottom of the tank, one at the top of the tank and a new larger vent. From the back of the car, I was going to run 1/2" flexible line from the tank to the frame section located right before the rear wheel and then convert to 1/2" stainless tubing (0.028" wall tubing). Reason for the conversion to tubing is that I need to run the tubing through the frame (front of the car) along side of the 5/16" factory fuel line and the area where the fuel line pass THROUGH the frame looks to be too small to accommodate a 1/2" hose along with the 5/16" tubing. I plan to use the 5/16" tubing for either a bypass system like Cliff uses or vapor return line for a mechanical system.

So, here are my choices:

1. Comp 140 electric back at the tank with a RobbMc pre-filter. Mount a RobbMc fuel pressure regulator at the motor and right before the regulator, insert a T in the line to recirculate some of the fuel back to the tank (Cliff's design). Run a RobbMc post filter.

2. RobbMc 1100 series mechanical pump up front with a RobbMc regulator. Run a RobbMc pre and post filter and install a vapor return fitting on the regulator to send back a small portion of the fuel to the tank to reduce possibility of vapor lock.

Both options are a big investment for me and without any real experience with either option, I am in a deadlock situation.

Electric pros and cons:
+ when plumbed properly, constant supply of cool fuel to the carb
+ remove clutter at the front of the motor except for the regulator.
- Not as reliable??? Reports of people losing an electric pump without much warning.
- electric draw on the alternator - even as small as it is, there is still drain on the system.

Mechanical pros and cons:
+ Very reliable - not too many reports of the pump just dying.
+ the 1100 pump can be used with an external regulator, improving delivery and the ability to run lower pressures to keep from over driving the carb seat.
+/- Can recirculate a small portion of fuel like the electric however the potential exists for heating the fuel
- lots of equipment to fit in a small space by the motor. regulator will see some heat from the motor.
- reports of some that run out of fuel on the top end.
+ Excellent customer support

Am I over thinking this to the max??? Just want a reliable car that I can get in, hit the key and not have to worry about carrying around spare parts with me.

Opinions welcomed. Thanks...

[Scott Stoneburg]

I also agree that you probably dont need 1/2" line. i ran 3/8 line and a holley blue pump for years of trouble free street driving and weekly trips to the drag strip.( not to mention the sometimes bi-weekly trips to the "bridge" for some play time.) i went as fast as 10.60s @ 128 with this set up. i agree that the RobbMc mechanical pump is a good option due to the mechanical nature and worry free aspect. just dont over think it. if your goal is not serious drag race only the your putting in way to much fuel. just my .02.

[Tom Vaught]

I have seen several Mopars run mid 10s with a 3/8" line and a pusher pump.

Tom V.

[66bonne]

Have to agree that 3/8" line is fine for the street and would also be fine for the strip in your application.
I also suggest either of the RobbMC pumps tho' the smaller of the two would supply plenty of fuel for you.
All that being said - if you elect to go with the 1/2" line I would go with the mechanical pump set-up. More reliable, easier to install.

Good luck, Jim

[rod cole]

Electric pumps are noisy no matter who makes them. The mallory is a good pump but is loud and not that reliable I have one and has stopped once and froze when I turned a corner low on gas less than 6 months old. I would just put the large factory replacement pump on it and drive it.

[Schurkey]

HOW MANY HORSEPOWER???

You need just over 1/2 pound of fuel per horsepower per hour.

500 horsepower X 0.6 pounds of fuel = 300 pounds of fuel

Gasoline weighs about 6 pounds per gallon

300 pounds per hour / 6 pounds in a gallon = 50 gallons of fuel per hour.

You need that 50 gallons (actually, 50 gallons is generous if the engine is properly jetted and tuned properly) at the carb; and delivered at the appropriate pressure.

If you're running a return style regulator, you need to add all the returned fuel to the 50 gallons actually burned.

First Guess: 1/2" tubing is so overly huge as to be comical for 90+ % of street-driven cars.

[HWYSTR455]

Do it once, and not keep throwing money at it. I understand that theory all too well. From that line of thinking, you can't plumb it ONLY for what your setup is now, but also for any possible future combo too. Now, you may not have the money, or want to spend that much this time around, but you can still PLAN on having the end design system in mind.

That all being said, if you're going to replace the lines that run front to rear, do it with a pair of 1/2". Take your time routing it, make it neat and mount it properly, and it will give you years of service. Cap off what you don't use if you choose. Talk to some of the fuel & brake line companies and have them send you pre-bent ones. (It's not like no one has ever done this before).

For the tank, have a sump installed, and baffling if you can. Better yet, buy an EFi ready stainless tank from a vendor, most already have mulitple fittings, vents, baffling, and sumps built in. So in the year 2030, when they make no-slip tires, you won't fuel-starve leaving an LED or hologram traffic light.

Pump selection even to this day (after all I've gone through with systems) can require additional thought. Personally, I have not had good luck with the Comp 140s. Others I've tried (electric) are way too loud, UNTIL I found the Holley HP150. Can't even hear it. If you choose to run a mechanical now, just design/route the lines so that in the future you could add a pre-filter and electric pump. And never say never. You may one day want to convert to EFi. For now, your setup would probably be a good candidate for a mech pump, and the RobbMc stuff is the hot ticket.


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