Fuel Line System and Size

[cv2065]

I'm planning out my fuel system and will be going with Nicopp again, as I had great success with it before and the Ham-Let fittings. Looking at a 427 carb'd engine, pushing around 550HP. I'm planning the Aeromotive stealth 340 pump and hangar (18638). I know that's overkill with the pump, but I love the Aeromotive stuff and that worked fine last time. I'm also looking at the Aeromotive 13220 FI to Carb Fuel Regulator and the Aeromotive 12330 40 micron inline fuel filter.

That said, I'm seeing conflicting info around feed and return line size. I used a 3/8" feed and return on my last build, but this pump assembly states in the directions:

10. Connect the supply and return fuel lines to the new Aeromotive fuel pump assembly. Note: AN-08 lines will be required for carbureted applications, AN-06 or AN-08 lines may be used for EFI applications

Any ideas why it might require the larger line? Another thought is around the Aeromotive 18638 fittings which are 6AN. I can get the ORB fittings that convert from 6AN to 8AN, but not sure how that enlarges the line since it starts off smaller. Unless of course because of the pressure, it really doesn't matter until it hits the regulator. Once the line is full, the pressure uses the larger tube to move more fuel than a 6AN line?

Anyone have thoughts here on which way to go?

[Jim1855]

Higher pressure of the EFI pumps will push more fuel through the smaller lines. I think that what they are recommending with the AN-8-1/2" lines is to reduce flow restriction. Probably a good thing and going from AN-6 to AN-8 isn't a big price bump.

?? Are you going to maximize the available power of your 427? If so, I wouldn't skimp on the lines.

I have run steel 3/8 line, filter at the tank and mechanical Edelbrock Vic, Jr pump to feed the 780cfm double pumper on my 427w, approx 535-550 hp. Worked well with a Aeromotive bypass regulator and 5/16 rubber return lines. Never saw an issue with many full power, 6500 rpm +, high speed runs and many dyno runs.

For the current build I'm planning on the same engine, carb and probably a Victor mechanical pump I'm planning on AN-8 PTFE SS braided line for the feed and either the same or AN-6 for the return, again with the same bypass regulator.

Jim

[Al_C]

In my experience, Aeromotive tends to be pretty specific. Case in point - when I first installed my regulator, it had "generic" fittings connected to it. It leaked. When I contacted them for help, they asked for a photo and pointed out I was using non-Aeromotive parts. Sure enough, their parts worked fine. Granted, that's only one example, but based on that, I'd go with what they recommend. AN8 is huge, but so what?

[cv2065]

Higher pressure of the EFI pumps will push more fuel through the smaller lines. I think that what they are recommending with the AN-8-1/2" lines is to reduce flow restriction. Probably a good thing and going from AN-6 to AN-8 isn't a big price bump.

?? Are you going to maximize the available power of your 427? If so, I wouldn't skimp on the lines.

I have run steel 3/8 line, filter at the tank and mechanical Edelbrock Vic, Jr pump to feed the 780cfm double pumper on my 427w, approx 535-550 hp. Worked well with a Aeromotive bypass regulator and 5/16 rubber return lines. Never saw an issue with many full power, 6500 rpm +, high speed runs and many dyno runs.

For the current build I'm planning on the same engine, carb and probably a Victor mechanical pump I'm planning on AN-8 PTFE SS braided line for the feed and either the same or AN-6 for the return, again with the same bypass regulator.

Jim

Which regulator are you using Jim and which PTFE SS braided vendor? I thought about going this route and was thinking ok, so I buy this giant SS line, cut to length, then screw up the fitting. Then there goes a bunch of money.

[cv2065]

AN8 is huge, but so what?

I hear that. You have to a look at bit to get the Ham-let 1/2" hard line to flex fitting. Their site says 8 week wait time so had to look elsewhere.

[Jim1855]

Regulator is this or similar.
https://www.summitracing.com/parts/aei-13205

Fuel line, but I'm looking at options/suppliers.
https://irp.cdn-website.com/e112be6e/files/uploaded/those923.pdf
Will be AN-8 as a feed line.

This for a fuel log. Will need to add a port fitting on the back end for the line to the regulator. Feed the carb first, then run regulating circuit, then the return.
https://www.speedwaymotors.com/Speedway-Motors-Fuel-Log-for-Holley-Carburetors,358919.html

Fuel filter. Mine has replaceable fittings. Currently using AN-6, will switch to AN-8
https://www.cantonracingproducts.com/products/canton-25-918-cm-15-fuel-filter-recirculating-1-4-npt-y-block-filter.html
The Canton elements are big, never had a problem with the filter clogging up.

Mechanical fuel pumps pull and push fuel. Electrics are better at pushing, or so I've been told.

Jim

[Its Bruce]

I commented on this in a previous thread. For further reading that supports my commemts: https://www.onallcylinders.com/2016/02/11/carbureted-vs-efi-how-fuel-line-size-effects-pressure-drop-in-your-fuel-system/

If your regulator is near the engine, I wouldn't hesitate to go 6AN between it and the pump.

[cv2065]

Regulator is this or similar.
https://www.summitracing.com/parts/aei-13205

Fuel line, but I'm looking at options/suppliers.
https://irp.cdn-website.com/e112be6e/files/uploaded/those923.pdf
Will be AN-8 as a feed line.

This for a fuel log. Will need to add a port fitting on the back end for the line to the regulator. Feed the carb first, then run regulating circuit, then the return.
https://www.speedwaymotors.com/Speedway-Motors-Fuel-Log-for-Holley-Carburetors,358919.html

Fuel filter. Mine has replaceable fittings. Currently using AN-6, will switch to AN-8
https://www.cantonracingproducts.com/products/canton-25-918-cm-15-fuel-filter-recirculating-1-4-npt-y-block-filter.html
The Canton elements are big, never had a problem with the filter clogging up.

Mechanical fuel pumps pull and push fuel. Electrics are better at pushing, or so I've been told.

Jim

Thanks for the run down Jim. That fuel line place is not too far from me in Sarasota. Have to check them out. They also assemble hoses as well.