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Anybody else running 5/16 fuel line to 496?

7K views 35 replies 19 participants last post by  aukai 
#1 ·
Never checked my fuel line size all these years, today I was underneath the rear end doing some maintenance and figured I'd check fuel line diameter seeing it was staring me in the face, well its only a 5/16th line!!!
thought it was 3/8".....anybody else running the same size line going to 496? Car runs good so I don't really want to change it if not necessary!
Fuel pump is Holley mechanical 12-454-11, 110 gph
Thanks,Rob
 
#5 ·
boittom 11s at 120 on a 5/16 line. Yikes. Got pistons?
I checked plugs ,no signs of detonation, not running lean either! only spin to 6000 if that makes a difference.
 
#6 ·
Ok, by the sounds of it so far I think I better do a fuel line up grade...might be pushing my luck!
Thanks, Rob
 
#15 ·
5/16" fuel line, Holley Blue pump, Fram 90 GPH fuel filter. 10.3:1 383 SBC. Started having fuel supply/pressure issues in the 1/8 th mile at around 450 HP. Mid 7's at 93 MPH in 1/8th @ 3610 lbs.

-10 braided line, Mallory Comp. 500 filter and Comp 140 pump worked well at ~730 HP and 6.20's @ 111 MPH in the 1/8 th @ 3650 lbs.

Same line and filter with Magnafuel 500 GPH pump now.
 
#16 ·
Looks like the easiest would be to run 10 braided line with RobbMc pick up from tank to pump... should do it no?
Only raced this car 1/2 doz times, mostly street driven.
Thanks for all your input guys!!
Rob
 
#17 ·
Hook up a remote fuel pressure gauge and see what it does under WOT. If it holds pressure I wouldn't touch a thing.

That's exactly what I ended up with. Ran -10 from RobbMC p/u through a 100 micron filter >Holley mech pump > 40 micron filter > Holley regulator, split off two -8 to the bowls. This feeds 700 hp at 7k RPM with steady fuel pressure.

I must add, don't be an idiot like myself and run a 10 micron after the pump. It will kill your fuel pressure.

Hard line is the way to go, but as others said I don't think it's feasible with the body on.
 
#19 ·
-10 is excessive for basically a street car and even -8 is big, but -6's ID is smaller than 3/8 so I'd run the -8. A true 3/8 line would be more than adequate.
I'd go with -8 teflon braided line. Maybe keep the 5/16 as a return if the need ever arises.
 
#20 ·
You can run a hardline w/o removing the body, but it gets muddled up at the rear axle. I have a line run through the frame all the way to to engine fed by a braided line from the tank. Since I only sport maybe 525hp I didnt bother with any of the fancy stuff you guys are talking about. ;) You could also use alum line as it bends very easy. Either way, it isnt a walk in the park. You'd have to raise the body to snake it in like factory.

BTW Rob, 68 Beau has gotta be my favorite, right next to a 68 SS. Had a chance to buy one from a fella here back in 02/03 ( "snake" from ON) for 6K and its one of my biggest regrets. Yes I would have blasphemed it into a drag car, but....
 
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#21 ·
I think a good 3/8 line would work. I think some of the brake tube companies actually sell prebent line. The 3/8 flows 40% more than the 5/16 just to start. However, don't forget the in-tank line. I think you can get a sender unit with a 3/8 line. I think the later year big block cars came with 3/8 lines to begin with.
 
#22 ·
I too like the braided stuff, really nice, easy to work with. However, I don't like the price so much. So don't count out some of the blue push-lok fuel line. It will do the job just as good as the braided, and save some dimes on the hose and the fittings as well. Like any soft hose, it needs to be fastened secure so it don't rub a hole thru itself. I was always conrerned with the hose coming off the fitting, as there is no clamp or "nut" to hold it together.....until I tried to take a hose off a fitting...ain't no damn way that hose is coming off that barb unless you slice it across the barb...give it a try, you'll believe. Just for grins, if you ever have some laying around, and ur out in the shop with some buddies having a few cold ones, throw down a $5 bet to see who can pull a hose off a fitting...will make for some good giggles. ;)
 
#23 ·
Buddies 68 496 Chevelle ran the exact same set up.....5/16" line....Eddy 110 pump with no issues. He has now swapped to the Robb MC -8 pick up and kept the 110 pump. Car trapped 117 with both set ups.
 
#25 ·
Not trying to beat a dead horse here, but if you wanted some of the push lok stuff. I was looking at Speedway Motors, and they have blue or black colored hose. I thought it was just the blue. They also have black fittings if you wanted to stealth it or something. Looks a lot like rubber fuel line, just larger. It's thier house brand, so it's slightly cheaper than the Aeroquip or Fragola brands. I've used the house brand hoses and fittings, and it seems of good quality. Some of the Speedway stuff a guys gotta watch out for, but the hose and fitting stuff seems good.
 
#26 ·
As far as size goes, maybe an -8 would be fine. I ran dirt cars for years, 358 sbc that we spun to 8600. Had some kinda gas hog, almost 1000cfm carb, and always used -10 from tank to pump, then -8 from pump to carb. Always worked. Maybe was more than needed, but always worked. CV Products carter mech. pump as well. Never had issues.
 
#27 · (Edited)
So the in tank sending unit already is 3/8" don't know why it was reduced to 5/16 line from tank to fuel pump, it originally had a 307ci...going to get some good 3/8" hose and plumb from tank to fuel pump! :D
 
#28 ·
So the in tank sending unit already is 3/8" don't know why it was reduced to 5/16 from the factory, it originally had a 307ci...going to get some good 3/8" hose and plumb from tank to fuel pump! :D
It probably isn't reduced I would ck it my car had 5/16 from the sock on the pickup to the fuel pump from the factory. The factory sock can also cause major restrictions as others have stated a new 3/8 pickup and line and you should be fine.

Brian
 
#31 ·
-6 or -8 braided is easy to run. Just zip tie it to the frame. -10 is overkill.

If you want to do hard line and don't want to lift the body, do 3/8 copper nickle. You can bend it with your hands. So you could just feed it between the body and the frame by the rear axle, bending it as you go.
 
#32 ·
I recently posted this...I just ordered "The Right Stuff" prebent OEM type line...installed like factory. $90 for a SS 3/8 line. Summit: RSD-XGL6801S for a 68 Nova...my car is a Nova, but stuff is very high quality.

I believe they also offer 1/2 inch, but may have to go direct to the company.

My car is EFI so for a return...I just ordered another - durable and clean install.

14 03 30 Nova Underside
 
#33 ·
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