You are correct.
The return sees very little pressure, so you can get away with carb fuel line no problem.

Good luck!


-Ted

 

Cool! I'll Y the return line into two or three stock 1/4" lines that run the length of the car. No need to install a second 3/8" line.

By the way, It looks like 3/8" is a little bit large on the fuel rail nipples. I'm thinking 5/16" may have been a tighter fit, although my testing with standard carb 5/16" line proved very difficult to push on. I was going to use hose clamps instead of the stock mazda squeeze clamps anyway. Do you think screw-type hose clamps will be ok? Sorry for the newbie question.

 

Screw-type clamps on a 3/8" fuel line should be okay.
I would check them regularly in the first few weeks to make sure they don't leak.
I know the stock FC fuel lines are 5/16", but I dunno if it's applicable to your GLC.


-Ted

 

All three fuel lines on the GLC are 1/4" (send, return, breather). I connected all three together for a feed line for my carb with 3/8" on either end. Man, it flowed fast with a bunch of volume! I figured I'd need to add a real 3/8" line under the car when going EFI so the return line(s) wouldn't have to be at 1/4". I was affraid of creating a restriction.

I think I'll use the new single 3/8" line as a send and two 1/4" lines as a return. The remaining 1/4" line will be a breather since I switched to a fuel cell. I don't trust the stock tank breater stuff, so I'll just install a VW bug fuel filter in the breather line to act as an air filter and have it end either in the back of the car, or run it through the 1/4" line up to the engine bay. I'll need to vent the oil filler tube to prevent a nasty water buildup (especially in the long 20B tube), so I'll probably just vent fuel vapor and oil steam into the intake elbow. What do you think?

I wonder if it would be better to install in inline PCV valve and hook it into one of the primary runners?

I'll go back and check the fuel lines for sure.

 

Yea, I'm still around. Sorry, I've been working all the time and haven't been on the forum in few days. Your rails should be coming any time now in the mail.

 

Excellent! I'll let you now when they arrive.

 

jesse, i would not say i have all the answers but k i asked the same question for about 2 months before designing my fuel system so give me a holla next time you get a chance and we can discuss what i was told....

fuel pressure needs to be at least 1+1 to 1+1.5 (or) for every pound of boost at least 2-2.5 psi of fuel pressure.
Most injectors are rated at 45 psi when measuring the flow rates...

As said in this thread, the most important thing is to make sure your pressure maintains at the higher levels.

20psi of boost @ 45psi fuel pressure would be just perfect if you could hook it up!

 

bladz311, the rails arrived today. They look pretty good. Thankyou very much!!

 

Not a problem!