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I'm about to start wiring and plumbing my car. 66 Chevelle will Blue Print LS3 and 4L75E. Fuel will be fed from Tanks Inc tank with a 255LPH pump, through GM regulator and filter. I will have a II MUCH vent canister for the vent. I was thinking that I should get larger fuel lines in case I desire more power with turbos in the future, so I got PTFE lines and connectors in -8an. Not sure if that was a mistake as I see most fuel systems on -6an. Am I good with -8?
Jim, although I would prefer as much hard line as possible, the only down side I can see with -8 Line is at the Filter/regulator. When the -6 adapters are installed on inlet and return side, these two connectors are very close together. That might be an issue with -8. Now that I think about it, I'm not sure you'll find -8 adapters. Also make sure to use adapters that use the aluminum locking system not the style that use the plastic tabs. These tabs are usually blue, they are a week design.
I ran -6 SS line on a 500 RWHP LS2 sleeved and stroked to 427 cubes. No issues with fuel supply. C5 FFR. As said above you aren't going to get -8 fittings on inlet/return side unless the -8 PTFE fitting are the same size as -6.
If you are thinking about upgrades HP wise in the future the 255 pump could be too small? Maybe an adjustable fuel regulator from the start instead the C5 FFR that an -8 would work nicely.
I know folks running 8s with -8an fuel lines. I went overkill and did -10 feed to the rails, -8 crossover and -8 return in case some day I want to make 1500rwhp. lol
Jim, although I would prefer as much hard line as possible, the only down side I can see with -8 Line is at the Filter/regulator. When the -6 adapters are installed on inlet and return side, these two connectors are very close together. That might be an issue with -8. Now that I think about it, I'm not sure you'll find -8 adapters. Also make sure to use adapters that use the aluminum locking system not the style that use the plastic tabs. These tabs are usually blue, they are a week design.
Thank you sir. I definitely have the adapters with the aluminum locking vs the plastic ones. GatTagO (I believe) warned me of that. I'll check to see if the -8 fits on the regulator.
Originally Posted by LS1 TJ
I ran -6 SS line on a 500 RWHP LS2 sleeved and stroked to 427 cubes. No issues with fuel supply. C5 FFR. As said above you aren't going to get -8 fittings on inlet/return side unless the -8 PTFE fitting are the same size as -6.
If you are thinking about upgrades HP wise in the future the 255 pump could be too small? Maybe an adjustable fuel regulator from the start instead the C5 FFR that an -8 would work nicely.
Thank you sir. My engine dyno'ed at ~550 HP, so -6 would probably be enough, just prepping for future. And yes, the 255 might be too small with more HP and even with e85, but that's an easier change than re-running all the fuel lines
Originally Posted by Pro Stock John
I know folks running 8s with -8an fuel lines. I went overkill and did -10 feed to the rails, -8 crossover and -8 return in case some day I want to make 1500rwhp. lol
I am running -8 ptfe from the tank to my in-line filter, up to the back of the fuel rails (it’s wye’d) which then go to the adjustable FPR at the front of the rails.. then a -6an line to the tank.
im also running a Walbro 525 hellcat pump. Or whatever the brand is that racetronix sells that makes Walbros
this is for my 427ci. Made 515rwhp through a t56 magnum and 9” with 35spline axles.
OK, so I can confirm that only -6 will fit. I have a question about the outlet of the filter. I have a QD 3/8" to AN adapter. I searched and search, but how does this install? Just push it in until it clicks? I did that and there is a little play in it. It can slide in and out a touch. Is that normal? Thank you so much everyone.
Just thought I'd throw this up in this thread. I really like this but would like some feed back. I know some of the aftermarket versions of the GM filer/regulater had issues.
I would do Wix from NAPA or AC Delco. Both are more money than Summit. Nothing against Summit. I do not know where they source the C5 FFR filters.
I made the mistake of buying AC Delco "Gold" FFR's from a seller on another web site that had some C5 FFR's for sale. Bought two at $50 a piece. I installed one since my old one that was 14 plus years old. As soon as I fired it up it ran like crap. Smelled super rich. I put my fuel pressure gauge on the fuel rail and it showed 78-80 psi. Should be 58 psi. I contacted the seller and he said he would refund my money. Never heard from him again. I'm guessing China knock offs.
I would do Wix from NAPA or AC Delco. Both are more money than Summit. Nothing against Summit. I do not know where they source the C5 FFR filters.
I made the mistake of buying AC Delco "Gold" FFR's from a seller on another web site that had some C5 FFR's for sale. Bought two at $50 a piece. I installed one since my old one that was 14 plus years old. As soon as I fired it up it ran like crap. Smelled super rich. I put my fuel pressure gauge on the fuel rail and it showed 78-80 psi. Should be 58 psi. I contacted the seller and he said he would refund my money. Never heard from him again. I'm guessing China knock offs.
As I said I was aware of the poor quality after market versions. I'm running a GM version that is without issue, however this particular Summit branded filter has the -6 fitting built in. that's a nice feature.
With the Tanks inc tank you also will want to run a extended hose on the vent up into the rear spring perch’s. A vented cap can leak during acceleration. When you fill that tank full it’ll leak out the vent.
With the Tanks inc tank you also will want to run a extended hose on the vent up into the rear spring perch’s. A vented cap can leak during acceleration. When you fill that tank full it’ll leak out the vent.
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Fuel line size 
I have a question about the outlet of the filter. I have a QD 3/8" to AN adapter. I searched and search, but how does this install? Just push it in until it clicks? I did that and there is a little play in it. It can slide in and out a touch. Is that normal? Thank you so much everyone.
I'll send you a bill.