Fuel Line Size

[streak]

I'm building a 427 sbc and starting to run my fuel lines and everyone tell's me to run 1/2" lines but the holley blue pump and regulator have 3/8" inlets on them, The fuel cell has 1/2" outlet on it so do I have to buy 3/8 to 1/2 fittings? Or will the 3/8" line be enough?

[BracketNova]

I have half inch behind my black pump. the "right" way to do it is to use one size bigger inlet size (from tank to pump) than what you run from the pump to the carb to avoid cavitation.

[ytnova]

How much power and how fast is this thing going to be? Are you sure a blue pump is enough? A 1/2 feed to the pump and a 3/8 from the pump to the carb is safe for about 500hp and probably low eleven to high tens, but you are pushing it more than that and you could run into some fuel starvation issues. I am not saying it will not do better, it just that seems to be the safe point before you need some upgaded pump. Remember, if you run a 1/2 line to the front, the pump has to overcome the additional weight of the fuel when the car launches. If you had a gauge in the back, it will maintain say 10 psi, but the fuel would be stationary in the line and not be flowing into the regulator/carb. Hence the reason most fast cars have a higher pressure/volume pump with about 30+ psi to the regulators and then mount the regulators in front of the engine so the low pressure flows back to the engine. Most of us also run return lines with bleeders in them to maintain a full column of fuel to the carbs and/or nitrous selenoids. If you have plans to go faster, why not invest in a larger pump and the associated fittings/lines now and not spend your money twice? You could also mount a small cell and the pump in the front of the vehicle and not have any issues either. Just my .02 cents, hope this helps.

[streak]

Very good point about pushing the fuel forwards at launch, engine should be 600hp+ in a little chevy luv and stall at 5300-5500 should leave hard to get it up on top of the mudd and I sure don't want it to lean out. Know you have gave me alot too think about.

[Speedster]

I run the 1/2 hard line all the way up to the front and from regulators to carb i run AN -8 line.
A friend of mine runs an-6 all the way and he runs nitrous and runs mid 9's and dont have any proublem.

[ytnova]

Speedster, like I said, it can be done, I ran two blue pumps with a 6an line for each, one for motor, one for spray and got the car to run 9.50's. I got lucky and never hurt the engine, probably because it never 60 footed that well, but I would certainly not recommend it for anyone else. I have way too much money tied up in my combo to go and skimp out on the fuel system again.

[Speedster]

Speedster, like I said, it can be done, I ran two blue pumps with a 6an line for each, one for motor, one for spray and got the car to run 9.50's. I got lucky and never hurt the engine, probably because it never 60 footed that well, but I would certainly not recommend it for anyone else. I have way too much money tied up in my combo to go and skimp out on the fuel system again.

Oh I agree 100%. Thats why i run the big line even though it's probly over kill with a 12 second car? but if and when i go faster i will already have the big stuff and not have to buy all new stuff later.

[streak]

Thank's for the info guys there's alot of great knowledge on here. Today I went ahead and ran the fuel lines the way I planned, 1/2" from tank all the way up front to the regulator where I have two 3/8" lines coming off the regulator one for each bowl of the 1050.

[Speedster]

should work good for ya.

[Bruce69Camaro]

I run 1/2" from my cell to the pump/ filter and then 3/8" the rest if the way up.

Actually, the famous Ed Bigley (1320racer) made a very good point on this subject and I have to agree with him that why would you want that extra fuel weight in your lines if your motor is going to be using it. Those weren't his extact words but it made sense if your motor isn't a high horsepower motor and doesn't need 1/2" lines to supply it, why have it and all that extra weight of the fuel, which gas weighs what, 8?? per pound?

Bruce

[streak]

Fuel weighs the same in the fuel line or in the fuel cell, three gals is three gals just wanting to make sure the 600+hp keeps plenty of fuel.

[BracketNova]

I'm assuming he's referring to pushing that weight. Especially when it's compounded with 1 to 1.5 gs of force when you launch. But, I had to read it twice too

[ytnova]

Correct spaz. If you have one gallon of fuel in the line, lets say 7 lbs worth, the car is launching at 1g and the pump only puts out 7psi, the fuel doesn't move even though the gauge would still read 7 psi.

[streak]

I thought you meant the weight of the fuel sitting in the line, might go with the black pump as you guys said makes alot of since and the plumbing is already there. Fuel line is only about six foot long.