Okay, I just finished ripping out all the stock fuel lines in my car. So, now I'm starting from scratch and I'm not exactly sure what to do.

First question: Material? Aluminum, Steel, Stainless (in order of cost)? I'm thinking of just going with steel since it's available and comes in lots of sizes (where aluminum seems to only come in 3/8, 1/2, 5/8).

Second question: Size? I know John Bzdel used 3/8 and 5/16 feed/return. But it seems like that choice was dictated by the availability of an OEM line. Since I'm starting from a roll of hardline, should I stay with that size, or step up to 1/2 feed, 3/8 return? The corresponding flex lines and fittings are AN -6 and AN -5, right? Well looking at the suppliers (Jegs and Summit - anyone know of any others?), -5 is just not available. The -8 and -6 are plentiful though. I'm going to be using the stock FBody pump (and regulator and sender, etc.), so will 1/2 be too fat for the pump? Is it a moot point since the engine won't even need that much fuel? I don't plan on forced induction or anything in the future.

Also, surely there must be such a thing as an AN female flare hose end that will connect to standard flared tubing fittings? I haven't been able to find one - or else I just don't understand the nomenclature for these fittings. I'd like to be able to just slide a fitting on the hardline and double flare it rather than having to braze on a fitting.

Third question: Routing. The stock location of the lines on the Z are in the trans tunnel. I've heard that some santioning bodies don't like this (in case the trans blows up I guess). I do plan on putting the car on the track at some point. The alternative is to route them along the shallow frame rail (which is really more of a floor support). Anyone have any thoughts on this?

Thanks.

 

It took me the longest time to figure out what AN size corresponded to what pipe size. <img src="gr_emb.gif" border="0">

Here is what I finally figured out. Take the AN number and divide it by 16. That will give you the corresponding pipe size. As far as I know there are no odd AN sizes. <img src="gr_sad.gif" border="0">

-8AN = 8/16 = 1/2pipe
-6AN = 6/16 = 3/8pipe

Those are the two sizes you want if your going to use 1/2 and 3/8ths line.

You should be able to feed one hell of a motor with a 1/2" supply. <img src="gr_stretch.gif" border="0"> I would think the stock pump will be able to keep the line filled unless your going with a 422 with all the goodies. Then I would think about upgrading pumps. The big line will increase the volume of fuel that needs to be in the line to keep a certain pressure but, the motor is still only using a small fraction of that. A pressure drop should only be a problem if the motor starts pulling more fuel from the line than the pump can supply, it should take a very healthy motor to do that though. <img src="gr_eek2.gif" border="0"> I could be wrong on the above though, I'm just taking a guess. <img src="gr_stretch.gif" border="0">

I don't know about the sanctioning body fuel line rules.

Johnnie

 

Thanks for the AN size conversion info - it all makes sense now.

I guess what I'm worried about is the stock pump being able to pressurize the fatter pipe. Makes me think that I should just go with the 3/8 line. Which leads me to another question: Must the return line be smaller than the feed? Since it looks like all I can get in the way of AN fittings are -6, plus the fact that the hard line comes in 25 foot lengths and all I need is about 9 feet, it would sure make things easier if I could just run 2 3/8 lines, one for feed and one for return.

 

What is the inner diameter of the stock fuel lines you took off?

A piece of -6 braided line is 5/16" id. I don't have a piece here but, I think a -8AN line is around 7/16" id.

About the pump being able to supply enough fuel to pressurize the big line, I don't know for sure. It seems that the amount of fuel the motor uses would be the deciding factor(not line size, to a certain point anyway). On either a big line or small line the pump only has to replace the amount of fuel that the motor is using out of it. I think you would be fine running the 1/2" line but again I'm just guessing. Maybe somebody else with a little more fuel system experience will jump in here. <img src="gr_stretch.gif" border="0">

What do you want to use the flared fittings for? <img src="images/icons/confused.gif" border="0"> Are you going to run a length of braided line off the hard pipe? There are AN fittings that connect to hard pipe. They are compression fittings. Whatever size tubing you go with you just use the corresponding AN size for the fitting.

Lets get this back "ttt". Could we get a little help in here please. <img src="gr_stretch.gif" border="0">

Johnnie <img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

 

I'm basing almost all of my info on John Bzdel's website. He has hardline 3/8 feed and 5/16 return with brazed fittings. I presume those are OD sizes. I know the other guy with an LS1 in his 240Z is using the stock Datsun lines (when I said stock earlier, I meant stock GM). He's still making good power, etc. (stock Datsun is I think a 5/16 feed and a 1/4 return).

I really don't know anything about AN fittings or lines. I don't need to run flared fittings, I just prefer not to braze fittings. If there's some sort of ferrule/compression type thing that wil work with steel, then that's fine by me. Is that the typical setup with this AN stuff?

SO, right now it looks like I have 2 possibilities on the table: 1/2 hard plus -8 soft feed with a 3/8 hard plus -6 soft return, or a 3/8 + -6 feed and return. I prefer the latter cuz it saves me a few bucks, but I obviously don't wanna go with a wrong setup. I'm taking stainless off the table because I fear it will be too hard to work with and it's an extra, unneeded expense. SO, the material will either be plain steel or aluminum - most likely steel.

[ January 30, 2002: Message edited by: jeromio ]</p>

 

Ok, that clears things up. I was confused on what you were doing. <img src="gr_emb.gif" border="0">

I think you will be fine running the same size feed and return. The lines are real close to the same on the stock setups that have full return lines anyway. That'll save you a little money just buying the 3/8ths 25' roll.

Here is a link to some pictures I took of the Earls AN fittings you need to go from hard line to braided.

http://community.webshots.com/script...bumID=27880962

Either Summit or Jegs has them or, if you've got a hydraulic fitting store close by you should check with them. Those places are gold mines when your looking for a certain type of fitting and they're cheaper too. <img src="gr_stretch.gif" border="0">

I'd go with steel on the lines. I don't like that thin a$$ aluminum fuel line. It just doesn't look sturdy.

Johnnie

 

jeromio, unless you are going to do 1000+ hp the stock 3/8" & 5/16" return lines are fine. I've seen Turboed cars use these size lines making 700+ HP without incident.

The reason I went this size was because these are the OEM sizes and I wanted to retain everything OEM appearing plus they matched the sizes on the C5 fuel rail.

As for material, I'd go stainless just to prevent rusting because they will be exposed to the elements on the underside of the car.

As for location and routing, I'd stay away from the trans tunnel in the event of clutch failure. You could have an exploding disc sever the fuel line and this would be big trouble! I would route along the outside of the car in the frame.

And yes, female connections are available. This is what I used on my braided stainless lines to conenct the hard fuel lines to the fuel rail.

Hope this helps!