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Discussion Starter · #1 ·
I'm going non-donor carbed and want to use nylon lines to the front then convert to braided stainless to the carb for a nice appearance. I have 351/408 w/ 780 Street Avenger. Is 1/2" feed and return OK?

Thanks, John
 

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More than enough. I have AN8 (1/2") send and return lines on my 650 HP BB

2FAST
 

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Wow! 1/2" lines?? So for our 400HP 351W we need to use more than the single (no return line) 5/16" line we had planned??
 

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Depending on your setup, most carbed implementations won't need a return line. Otherwise, the 3/8" line that FFR supplies is sufficient.
 

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Discussion Starter · #5 ·
Yeah, John Hudson has a little chart on his fuel line section where it reccomends 1/2" lines up to 550HP. Sorry-- My only New Years resolution is to learn how to post pics here and to cut and paste! I better start now cuz it'll probably take me the whole year. :D

Gremlins--we need more Gremlins
 

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We are using the stock tank. The pickup line into the tank is only 5/16". Does that mean we need to relace it with a 3/8" line? I figure we could fabricate our own tank insert out of plate with a 3/8" pickup. Has anybody else done this?
 

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For an excellent article on fuel systems check out this link:

FUELISH TENDENCIES ... How To Set Up Your Fuel System Correctly

I am certainly not an expert but in talking with tech support at Mallory and reading various articles - it seemed that a return line was the way to go



Do your self a favor, call Mallory and ask the experts. Here is a link to their phone number and email address

Mallory recommended that I use a 1/2" return line and a 3/8" feed line



Mallory Technical Help

[ January 06, 2004, 05:40 PM: Message edited by: John / My427SC ]
 

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I am running a 427 stroker around 500 HP with a 1/2" supply line and no return. Just make sure that you use a filter also.
Todd
 

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428FE with 3/8 line and Carter mech pump with no issues.
 

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I'm using the Moroso return style fuel log pressure regulator and those instructions also called for a larger RETURN line than feed. Talk about catching you off guard. I wound up like John Hudson with a 3/8 feed and 1/2" return.
Frank
 

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Discussion Starter · #11 ·
I'm basically using John Hudson's fuel system setup only with a larger displacement, EF 351/408 stroker carbed, about 500HP. Will I be OK with the 3/8 feed line or the 1/2? I'm gonna go w/ the 1/2 return line.

Thanks, john
 

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Discussion Starter · #12 ·
I contacted tech support at Mallory and they said to use the return line setup as pictured above and use 3/8" feed lines and 1/2" return lines.

John
 

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Bobby, I was thinking the same way before I got my new regulator. This was a total change for me from what I had always known about fuel delivery. The Moroso instructions specifically state that the return line must be larger than the feed. Apparently Mallory feels the same way. In thinking this through they must be concerned with avoiding return line restriction that would raise the line pressure. Also, since the pressure is regulated after the carb is supplied, there is nothing to restrict volume to the bowls so I'm pretty comfortable with a 3/8" supply line and 1/2" return. With a dead head regulator, pressure and volume are restricted by the orifice size BEFORE the carb and I used to run a 1/2" supply and TWO regulators to keep the carb fed with that setup. I think the return style is a much more efficient arrangement.
Frank
 

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Wow you guys are in overkill mode with the 1/2" fuel lines. I used 1/2" for my 850+hp blown BB chevy with 2 Holley 750dp carbs and BDS said that was plenty. You know most high perf cars in the 60's running 454's and 427's with one or two big holleys only had a 3/8 line.

With a return system if the regulator is controling the fuel bypass then nearly any size return line will do. You don't want the return line to be what is regulating the fuel flow.
 

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TMC,

I'm on your page! I guess ol' Shel didn't know what he was doing when he ran the 3/8" line on the original dual quad 427's, or Chrysler with their Hemi setups! No wonder those cars couldn't get out out of their own way - and we thought it was only the extra weight :eek:

What are you guys running for jets in those carbs that require that much volume? I find it pretty odd that you would need supply lines that are the same size as the water supply lines in a home. At the rate of flow that they would provide you must have to fill up by the time you reach the end of your street. And I thought mine was bad on mileage at 13 with dual quads!

[ January 09, 2004, 12:03 PM: Message edited by: B+L FFR 1686 ]
 

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One more note on large fuel lines from the pro-street days, you need a big fuel pump with that big fuel line. Remember your trying to move a large column of fuel, when you accelerate real hard all that weight stays in place as the car moves forward and the pump has to overcome it.
 

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So those of you with 400HP+ motors and stock fuel tanks--- What did you use for a pickup in the tank?????
 
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