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?
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.
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?
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.
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.
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.
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.
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
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!
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.
A forum community dedicated to Factory Five owners and enthusiasts. Come join the discussion about performance, racing, conversions, modifications, troubleshooting and drivetrain. We discuss MK4, GTM, 818, Type 65 coupe, roadsters, and more!