More fuel line help...questions

[allcarfan]

I ordered my new fuel sending unit. Virginia Classic Mustang told me that the hard line on it is 3/8". Again, I must commend VCM for great customer service and fast shipping. Anyway...I had ordered a hard fuel line from summit...3/8" also.

After speaking with many people I decided on a 3/8" line for my 475hp carb engine. Well, upon looking at the line and the sending unit...and measuring....the ID is 5/16" and the OD is 3/8"

My question is...when you order a fuel line or when im given the advice of "you should use a 3/8" fuel line"...does that mean I should order a 3/8" fuel line or does it mean I need a 7/16" fuel line with an ID of 3/8". Does that make sense?

Do I need a 3/8" ID or OD fuel line?


Shane

 

[66P51GT]

You risk running lean with either size. With that much HP, you may get away with a 3/8" line to the fuel pump, but you will want 1/2" ID to the carb.

Use these figures as a fuel line sizing standard:
Up to 250HP = 5/16" or -04 AN
Up to 375HP = 3/8" or -06 AN
Up to 550HP = 1/2" or -08 AN
Up to 800HP = 5/8" or -10 AN
Up to 1200HP = 3/4" or -12 AN

http://www.centuryperformance.com/fuel.asp

 

[allcarfan]

yeah, we have all picked that website apart before in two other recent threads. The numbers posted are a little 'off'

My question wasnt "is 3/8" enough." My question is when I place an order for a 3/8" line and receive it...the ID is 5/16"....is that what someone means when they say to order a 3/8" line? Or should I have ordered a BIGGER size so it will have an ID of 3/8"?

 

[66P51GT]

we have all picked that website apart before in two other recent threads

Gotcha... I'll search for the other thread regarding line size.

You should order the line that has the 3/8" Inner Diameter. this is the type of line that can be used with -06 AN fittings.

E.g. I'm running -06 AN steel braided lines from my mechanical fuel pump to the carb. These have approximately 3/8" inner diameter.

The stock hard-line is 3/8" OD with 5/16" ID. This wouldn't suffice for my (wimpy compared to 475HP) 380HP engine.

I checked the Summit catalog and they sell 3/8", 1/2", and 5/8" ID aluminum lines.

 

[allcarfan]

Ya, im thinking that I need to order the 1/2" OD line....and im gonna have to tap my gas tank and run a barb fitting for a larger line....fun times.

 

[mustangracer]

(E.g. I'm running -06 AN steel braided lines from my mechanical fuel pump to the carb. These have approximately 3/8" inner diameter.)


Not true I think, the diameter (-6) is OD. 3/8" hard line is 3/8" OD. That's why you use 3/8" ID hose to join it.

Don't mean to step on toes, but check summit's site, the russell line in particular explicitly states OD.

IN general though 3/8 line you buy aftermarket is thinner wall than stock, so it does flow more anyway. And Shelby used 3/8 for his 375 HP 289's.

 

[mustang2]

I'm following along with what you guys are saying. But if the sending unit is a 3/8" OD how do you get around that. Are'nt all the sending units 3/8" OD?

I'm trying to figure out how to explain what I'm thinking.
You put 3/8" OD line on the sending unit. And then right off the sending unit can you put in a barbed fitting and step up to a larger size line?

Would it make any difference doing this, since what's coming out of the sending unit is restricted anyway to 5/16" ID?

 

[allcarfan]

You can have a different tube brazed onto your fuel sending unit.

I am having a fitting brazed directly onto my tank and then running a barb fitting screwed into it. It will be cheaper and less labor intesive to have that done rather than having someone take apart my sending unit for a new tube. I am blocking off the 'stock' tube.

I spoke with my engine builder last night. id trust just about anything this guy says. He was telling me that a lot of 400+ hp cars run a 5/16" ID line and have no problems whatsoever.

However, I am ordering some NEW line from summit. Anyone need a 25ft roll of stainless steel 3/8"OD hard line?

 

[66HertzClone]

Hose is measured by I.D. tubing is measured O.D.

I also agree with the above post, you would have to be running extremely high revs for a long, long time before you would "run out of gas" using even a 5/16 OD line. Remember you will have to empty two carb float bowls, the line between the carb and pump, and the pump. While you are trying to do this the pump is working to keep up. You could always run a 3/8 or AN 8 line between the pump and the carb, the extra volume there should be more than sufficient.