[67Lemons]

Originally Posted by JLMounce

If you think about how this works in an EFI vs a carbureted platform, it makes a bit of sense.

There's far less pressure in the fuel lines when running this system carbureted, so there's more fuel flow (flow increases and pressure decreases) which would cause some friction heating as the fuel flows through the lines.

Because the carburetor also has fuel bowls that act as a reservoir, you're passing much more fluid through the whole system at all times. The larger line slows down the column of fuel, which in theory should create less fuel heating.

I don't know if that's really going to be a huge concern or not though. You can always run an inline heat sink too if it ever becomes a problem.

It almost sounds as if it would be better to run a short loop by mounting the regulator near the tank so no warm fuel enters back into the system?

[Gator67]

Could also run a Vaporworx fuel controller to control pump speed based on demand. This will minimize fuel through the return when there’s low demand, and so you could potentially get away your existing return line. There are other benefits to the pump not running full blast all the time. I run these controllers on two cars with EFI, but I believe they can be set up for carburetor as well. Carl Casanova, the company’s founder/engineer/designer has always been super helpful and responsive, so maybe worth reaching out. vaporworx is now part of Aeromotive but I believe Carl is still around.

[FrankieT/A]

My only suggestion would be to install a fuel pump/sender access door in trunk. Tanks Inc. sells them...

[jhein]

Originally Posted by JLMounce

If you think about how this works in an EFI vs a carbureted platform, it makes a bit of sense.

There's far less pressure in the fuel lines when running this system carbureted, so there's more fuel flow (flow increases and pressure decreases) which would cause some friction heating as the fuel flows through the lines.

Because the carburetor also has fuel bowls that act as a reservoir, you're passing much more fluid through the whole system at all times. The larger line slows down the column of fuel, which in theory should create less fuel heating.

I don't know if that's really going to be a huge concern or not though. You can always run an inline heat sink too if it ever becomes a problem.

OK, but for the carb application, isn't the pressure only lower on the carb side of the regulator? Why would the pressure be lower in the feed line in a carb application?

I'm not saying that I won't do the -8 lines, I just want to understand why and make sure it's necessary before I start returning parts and piecing a new system together.

[jhein]

Originally Posted by FrankieT/A

My only suggestion would be to install a fuel pump/sender access door in trunk. Tanks Inc. sells them...

That is my plan but I'm not going to do it right now. If I do it it will be ugly. If my car guy does it, it will look nice.

[Jay S]

I have tanks systems feeding a carb, there are a few different issues that you run into feeding carbs versus FI systems. When feeding a low pressure carb the pump flow rate is about 30% higher at 7 psi than feeding 40 psi on a EFI system. All that extra fuel gets returned constantly unless your at full throttle, with the extra fuel flow the fuel is extra warm when pushed thru a 3/8” line. I have noticed fuel even gets warm thru 1/2” line on my cars with the tanks system. With the small line and oxygenated fuel, feeding a carb, fuel pressure is not as consistent, and depending on the fuel and your carb set up vapor locking can be an issue. It isn’t that the 3/8” line won’t work most of the time, it will, but it does not work near as good as 1/2” line when condition that are hot or feed near as much HP.

With a carb set up the best results are to set it up so the fuel line from the pump to go directly to the carb and the regulator plumped in after the carb. Similarly to what I am saying with 3/8” line versus 1/2” line, it isn’t that you can’t put the regulator before the carb and plumb into the return, but it works best set up differently, less prone to vapor locking and more constant supply.

If you were determined to run 3/8” line, you might look into using a smaller 190 pump instead of a 255.

[Jay S]

No matter where you put the pressure regulator fuel pressure at the pump is basically the same as the pressure at the carburetor . The only difference in pressure at different points in the system is from friction loss in the line.

It would take another regulator in the system to effect the pressure at the pump. Such as one set at 40 psi to force fuel thru a smaller line, then another to drop the pressure more for the carburetor. That would force more fuel thru a small line, it fix’s one issue, but then the fuel pump wears out sooner because it is working harder, especially without a pump controller.

Skip Fix early mentioned he noticed the fuel got hot when he had is Mallory 140 pump pushing thru a mechanical pump. That Mallory pump was a lot bigger than the mechanical pump, it is a 140 pump pushing thru a 80 pump. That was a miss match kind of similar to how the 255 pump is with 3/8” line feeding a carb.

[grivera]

To me, there is no downside to 1/2” lines aside from price. It’s like the IAII block in your build- total overkill for what you do with the car but no downside and you never have to worry about it again.

[jhein]

Originally Posted by Jay S

No matter where you put the pressure regulator fuel pressure at the pump is basically the same as the pressure at the carburetor . The only difference in pressure at different points in the system is from friction loss in the line.

It would take another regulator in the system to effect the pressure at the pump. Such as one set at 40 psi to force fuel thru a smaller line, then another to drop the pressure more for the carburetor. That would force more fuel thru a small line, it fix’s one issue, but then the fuel pump wears out sooner because it is working harder, especially without a pump controller.

Skip Fix early mentioned he noticed the fuel got hot when he had is Mallory 140 pump pushing thru a mechanical pump. That Mallory pump was a lot bigger than the mechanical pump, it is a 140 pump pushing thru a 80 pump. That was a miss match kind of similar to how the 255 pump is with 3/8” line feeding a carb.

OK, that makes sense now. So the regulator just bleeds off enough fuel through the return line to keep the pressure wherever you set it for the whole system. And I can still run a 3/8 line from the regulator to the carb, if I keep the regulator before the carb, correct? So then really, I'll have all these expensive fancy fittings for a 7 psi system? That's kinda funny.

[Jay S]

Originally Posted by jhein

OK, that makes sense now. So the regulator just bleeds off enough fuel through the return line to keep the pressure wherever you set it for the whole system. And I can still run a 3/8 line from the regulator to the carb, if I keep the regulator before the carb, correct?

Yes you can run the 3/8 line to the carb from the regulator.

It is generally best to use a T in the fuel line before the regulator, and put the regulator after the T that feeds the carb, it maximizes the flow to the carburetor.

[jhein]

Originally Posted by Jay S

Yes you can run the 3/8 line to the carb from the regulator.

It is generally best to use a T in the fuel line before the regulator, and put the regulator after the T that feeds the carb, it maximizes the flow to the carburetor.

So just the input and return lines will be used on the regulator and plug the output side?

[Jay S]

Originally Posted by jhein

So just the input and return lines will be used on the regulator and plug the output side?

Yes. That is the best way to do it, but it is not always easy to make it look nice. If it gets to cumbersome looking just plumb the output from the reg to the carb.

[jhein]

OK, so I'll be sending the Tanks inc plumbing kit back. So now I need some recommendations for fuel lines, fittings and a regulator.

[Formulajones]

I've run these systems on carbs for years. What I do is 1/2" line with full length feed and return. I mount the regulator where the mechanical fuel pump used to be. Stays hidden that way. I like to use the Aeromotive 13301 regulator. It's ability to switch from carb to EFI is a nice bonus if you ever decide to change.

So feed and return go to the regulator, I then come out with 3/8 line to the carb. I typically bend up my own stock appearing steel line following the stock routing since the regulator is in the mechanical fuel pump location. This keeps things appearing stockish.

I've gone 10's at almost 130 mph with this setup and no issues with any vapor locking of any kind. I use 450 LPH pumps for those HP levels and drive them on the street in the AZ heat without issue. Basically when it's setup like this all you have to do is change the pump to support your HP level, simple as that.

[jhein]

Originally Posted by Formulajones

I've run these systems on carbs for years. What I do is 1/2" line with full length feed and return. I mount the regulator where the mechanical fuel pump used to be. Stays hidden that way. I like to use the Aeromotive 13301 regulator. It's ability to switch from carb to EFI is a nice bonus if you ever decide to change.

So feed and return go to the regulator, I then come out with 3/8 line to the carb. I typically bend up my own stock appearing steel line following the stock routing since the regulator is in the mechanical fuel pump location. This keeps things appearing stockish.

I've gone 10's at almost 130 mph with this setup and no issues with any vapor locking of any kind. I use 450 LPH pumps for those HP levels and drive them on the street in the AZ heat without issue. Basically when it's setup like this all you have to do is change the pump to support your HP level, simple as that.

Thanks FJ. What type of lines do you use, PTFE?

[Formulajones]

I get all my hose from ANhose fittings.com
I use the raceflux fuel and oil hose that's good for all types of fuel including alcohol, and it's nhra approved. If you look it up on their site it lists all the specs and what it's made of.
Right now they have a sale. 10 percent off $100 or more, 20 percent off $150 and 30 percent off $200 or more and they always have free shipping. The -8 hose is $7.89 a foot.

[jhein]

Originally Posted by Formulajones

I get all my hose from ANhose fittings.com
I use the raceflux fuel and oil hose that's good for all types of fuel including alcohol, and it's nhra approved. If you look it up on their site it lists all the specs and what it's made of.
Right now they have a sale. 10 percent off $100 or more, 20 percent off $150 and 30 percent off $200 or more and they always have free shipping. The -8 hose is $7.89 a foot.

Thanks very much for that FJ. I was feeling a little frustrated yesterday looking at hose and fitting options but ANhosefittings.com is awesome. I like that RF hose, looks very nice. They also had all the hose ends, fittings and adapters. Plus 30% off saved me $133.08! Awesome.

So I'm ditching the Tanks plumbing and I'm using -8 feed and return then -6 from the regulator to the carb. I'm going to use a Holley regulator that has a port for my pressure gauge and it's black so it will blend in better on the firewall. For my carb line, I'm going to run the -6 line from the regulator down to the mechanical pump area and use a hard line to -6 adapter to connect to the factory hardline so it will look totally stock.

[grivera]

What is the model number for the Holley FP regulator you’re using?

[jhein]

Originally Posted by grivera

What is the model number for the Holley FP regulator you’re using?

12-841

https://www.summitracing.com/parts/hly-12-841

[HWYSTR455]

Strongly recommend using same size line for return, especially if you're using a larger pump. You could have an issue where the line won't return enough and you can't get the psi low enough.

I have a 13301 new regulator for sale at the moment:

https://forums.maxperformanceinc.com...d.php?t=882342

Nice thing on those is that you can simply replace the spring and it will work with EFI too.

Regulators should be as close to the 'load' to maintain psi best.

1/2" hardline routes easier than AN -8 or even -6.

With 'soft' lines in long runs, it is possible to induce pulsing of the fuel. You will know if you see the needle on the gauge fluttering.



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