bw71mach1

I have a 1971 351C that has been converted to a 408 stroker. I read in Mustang Monthly that you should increase the size of the fuel line from 5/16" to 3/8". What is your experience? Does 428 cars have different fuel line sizes from the factory?

barnett468

hi,

if you are going to be holding the pedal to the floor for 1/8 mile or more i would run 3/8". if not you do not need it.

67mustang302

Fuel line size is primarily dictated by horsepower of the engine and delivery pressure/type (EFI vs carb etc).

That said, 3/8 is a good size to provide the fuel needed more most street engines.

With stock heads and a mild cam, even a 408 can get by on 5/16.

dodgestang

My 410c would run 12.3 with 5/16 line and bad driving.
Once I learned how to drive better I was forced to upgrade it to 3/8 lines because it would run out of gas before the end of the race and require me to lift for a second and allow everything to catch up.

Even with the 3/8 lines however if I shift it at redline (7500 for me) I run out of fuel in the middle of third gear. If however I shift it at 6300-6500 in first and second it makes it all the way through the 1/4 miles without fuel issues.

Both 5/16 and 3/8 never gave me any issues on the street and the limitations only showed themselves at the track racing.

bw71mach1

So given I have a 600cfm 4bbl carb I'm okay with 5/16". If I go up to the 750 cfm it sounds like 5/16" is still good. I'm just using it on the street. Looking to get off the line better.

dodgestang

I think you will want a better carb than a 600cfm with a 408c personally

barnett468

Increasing your fuel line to 3/8" will not have any effect on how quickly you get off the line.



CARB

Your 600 is a bit small imo a 750 would be the max I would use.

Unless you have a monster cam and low gears like around 3.91 - 4.11. I would not run a double pumper carb larger than 650.

A 750 double pump will not get you off the line better because it will simply flood out most engines with the secondaries fully opened at 0 mph.

Even though I think any 750 might be a bit big unless you have a monster cam and turn high rpm's, I would run a 750 vacuum secondary annular boost venturi type like a holley street avenger. The quick fuels occasionally have probs.

You can adjust the secondaries to come in early, mid or late etc.



GEARS

Unless you have 350's or lower, you won't get off the line "fast" especially in a heavy car like that.