EFI tank with Carbureted engine plumbing questions

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cudajames

cudajames

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I am about to change my gas tank over to a tanks inc EFI with in-tank fuel pump and sender. I plan to use the Holly Carburetor Bypass Regulator (12-887)

My plan, install new 3/8s stainless fuel line, run it through 100m filter and then through the regulator to 40m filter and then through to the carburetor. The existing 5/16s will be used for the return line. (see image)

The 3/8s and 5/16s fuel line will be run side by side – anyone done this? How did you run the lines? I found some S Clips to help tie the lines together. (see image) Anyone know if there are C Clips to hold two lines?

The 100m filter/regular will be in the engine bay attached to the inner passenger side fender.

Am I missing anything?

View attachment 1715661424

C clips.jpg


s Clips.jpg


fuel line 2.jpg
 
selecting-the-correct-regulator-for-your-car2.png


I would suggest you plumb it this way. Reason being is that this actually controls the fuel pressure at the carb and it will not change depending on the condition of the fuel filter. Just imagine the hot rod pump being in the tank.

Fuel filters are pressure drops by themselves, and as they get more dirt in them, the pressure drop increases.

I did an EFI system and both the feed and return line are 3/8", I ran the return line down my subframe connector and then it went to a braided teflon line at each side at the engine and at the tank. It was just easier to do it with the -6AN fittings.
 
Imo you want to use the wrong fuel pressure regulator. The one you linked in you post is for a carbureted application with a low input pressure! There are dedicated FPRs for running carbs with an EFI pump. Directly from the Holley webpage:

"Most fuel pressure regulators are designed to operate either as a dedicated low-pressure device (roughly 3 to 16 psi) or as a high-pressure regulator (40 to 70 psi). Recently Holley has released a billet fuel pressure regulator that can do either job with a range of 4 to 65 psi (PN 12-879 or 12-880). The regulator comes configured as a high volume, low-pressure regulator but can be reconfigured to control high pressure just by changing a spring that is included with the regulator. This is designed for enthusiasts who are currently running a carbureted system that may at some point convert o EFI. This saves the expense of purchasing a separate regulator."

How to Choose a Fuel Pressure Regulator For EFI or Carb
 
Thank you @ChargerST for the catch.

I am diving deeper on getting this setup correctly. Tanks Inc recommends the Edelbrock 174053 regulator, I will be looking at the holley 12-880 (recommended by holley) and the Fuelab. I have sometime as I wait for the fuel tank and hardlines

I learned the feed line should be 1/4 to 3/8s and the return should be 3/8 - as goldduster318 - I will be running both 3/8s hardline
 
The Holley 12-880 regulator will work for you. You can use the existing 5/16 line for the return and use the new 3/8 line for the pressure side. You don't even need 3/8 line on the pressure side, 5/16 will work fine there too. When you have 60 psi in the fuel line the line doesn't need to be very large.
 
The routing in your first diagram will work.
Bypassing at the end of fuel log will work, too.
As far as fuel flow, pressure setting and line sizes, better do your home work or you'll be disappointed.
Read the posts starting here and the next page as the OP tests it out.
 
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As far as running the lines, just run them side by side or in the case of under the rocker, one on top of the other. The standard clips will hold one line unless you get clips for CA spec car of the era that had to have an evap system, then it should have dual lines. Normally if I only have the single clips, I put one line on top of or next to the other one and then use some zip ties about every 6" or so. Of course if you are handy with sheet metal you can make some dual clips that you just bend around each line.
 
Mattax said:
As far as fuel flow, pressure setting and line sizes, better do your home work or you'll be disappointed.
Read the posts starting here and the next page as the OP tests it out.
Click to expand...

Great read, actually went back to the beginning of the thread. I have some time before the tank and 3/8s hardlines arrive (oh the joys of a 1st gen cuda) to continue to researching regulators. Also continued reading about the pump, which has a filter built in, so I am currently leaning to go with a 40 micron before the regulator and than the straight into the carb.

A little additional information, at this stage I have zero plans to go fuel injection on this motor, so the Holly 12-880 is probably out. When I upgraded my rearend with a moser braced axle housing I lost to much clearance between the brace and the sender. In certain situations, speed bumps or turning into a driveway the brace hits the sender, gas comes out which I hear is a bad thing. I modified a new sender and attempted to clock it at a different angle with no luck. The EFI tank eliminates the sender in the side of the tank by moving it to the top and gives the additional clearance, which I believe will solve that problem

sender.jpg
 
cudajames said:
Great read, actually went back to the beginning of the thread. I have some time before the tank and 3/8s hardlines arrive (oh the joys of a 1st gen cuda) to continue to researching regulators. Also continued reading about the pump, which has a filter built in, so I am currently leaning to go with a 40 micron before the regulator and than the straight into the carb.

A little additional information, at this stage I have zero plans to go fuel injection on this motor, so the Holly 12-880 is probably out. When I upgraded my rearend with a moser braced axle housing I lost to much clearance between the brace and the sender. In certain situations, speed bumps or turning into a driveway the brace hits the sender, gas comes out which I hear is a bad thing. I modified a new sender and attempted to clock it at a different angle with no luck. The EFI tank eliminates the sender in the side of the tank by moving it to the top and gives the additional clearance, which I believe will solve that problem

View attachment 1715664229
Click to expand...
Glad you found it useful. We can learn from each other. :)
Seems to me that switching tanks is a good solution. Hopefully you can get a float-resistance arrangement to provide a semi-accurate indication of fuel level on the gage. That will be a challenge of its own as you probably know.
Filters. I agree. A carb doesn't need super fine filteration. That will be the same as it did with a mechanical pump. So it comes down to whether the electric pump needs something finer.
Could also stick with mechanical pump if you wanted. Biggest disadvantage is the long suction line. Advantage is no need to rework the electical system.
 
I went from the efi tank and pump to a carb by using a universal bypass regulator from ebay. Had to drill the return oriface bigger to get the pressure down far enough.
 
dusterbd13 said:
I went from the efi tank and pump to a carb by using a universal bypass regulator from ebay. Had to drill the return oriface bigger to get the pressure down far enough.
Click to expand...
Which regulator did you use? Name brand or cheap, knockoff version?
 
75slant6 said:
Which regulator did you use? Name brand or cheap, knockoff version?
Click to expand...
Cheap knockoff. Like 20 bucks or so. The oriface had to be opened significantly to lower the pressure enough. However, it works perfectly and keeps fuel cool and no vapor lock.
I also run 3/8 feed and 5/16 return.
 
dusterbd13 said:
Cheap knockoff. Like 20 bucks or so. The oriface had to be opened significantly to lower the pressure enough. However, it works perfectly and keeps fuel cool and no vapor lock.
I also run 3/8 feed and 5/16 return.
Click to expand...
Thanks! I was just looking up the regulators on eBay tonight and watching a bunch of review videos on them. I noticed today that my mechanical pump has started leaking, and I’ve been wanting to put the magnum serpentine setup back on the engine anyway, so I think I’ll get one of those regulators and go ahead and get the swap done.
 
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