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I am STILL installing a 2017 LT1 6.2 into my 1978 . I cut the fuel lines up front and modified the lines for AN6 and AN4 fittings which I ran up to the fuel regulator on the firewall. I am installing a new tank and fuel sender. I am wondering how others did the fuel lines at the tank.
Did they modify the lines to match AN fittings, or just clamped fuel hose to the original lines- possibly flare the ends and double clamp ? I am planning on just clamping the return line because there won't be any pressure build up .
So your putting the Filter/regulator up front? Most put it in the rear. Like GM did it. I run a 3/8th's inch return. Most do. Your AN 4 return sounds a bit small and it's terribly long.
I installed a new bulk head fitting for the feed in the top of the sending unit that was already setup for AN Fittings. I used the Factory feed line for the return. Cut off about 2 inches from the bottom of the tank and emptying into my fuel baffle.
my filter/regulator is in the right hand quarter panel about 6-8 inches behind the number 4 body mount. Fuel lines from tank to regulator run in the stock location. Then a feed line to the front also run in the stock location but of course without a return.
You’re gonna love that 6.2! I have a ‘17 Camaro with that motor and with the 8speed auto, they are an absolute hoot to drive. Broad, flat torque curve that pulls like a freight train.
On my 78 with and LS swap I’m running the stock 78 tank with a 82 sender with a walbro 255 HP. I used the stock sender lines for the pressure and return. I however am running a Ls filter/regulator combo back by the tank so the return is right there and back to the tank so that means I just have a single line going to the fuel rail from the filter/reg by the tank.
the sender has 3/8” hard line barb output which I run a 3/8” EFI rated rubber fuel hose double clamped (with EFi style hose Clamps) and end with a barb to AN hose end. That screws onto the filter/reg which has AN adapters installed already. The filter/reg has a built in return that’s 5/16 and I run an AN adapter to -6 or 3/8”. I then run a rubber hose from that back to the return line on the sender which a clamp off with 1 EFi clamp. The return line should be under much lower pressure so no need to go crazy. I then run a -6 AN PTFE braided hose from the filter/reg all the way up to the engine fuel rail using the stock hard lines as a guide. The fuel rail is capped on the driver side front so the system is basically a dead head 58psi fixed fuel system but has a return back near the tank to keep the pump happy and fuel cool. I normally like to run an external return style regulator near the engine but on this car there is no need as it won’t be boosted for a bit if ever. Actual fuel pressure is 61-63psi according to the Holley ecu with 100psi pressure inducer in the fuel rail.
You have a few options and I will assume you have a return and pressure line at the tank. You can use EFI rubber hose at the tank and connect to the stock hard line double clamp to be sure on the pressure side if you want. The rubber adapt at the front as well to the regulator which would be the easiest and cheapest as long as the stock hard lines are in good shape. You can run new braided lines (PTFE not regular braided) and adapt as necessary or cut the barbs off and try to do an AN flare on the hard line to adapt AN fittings for a cleaner install at the tank or engine bay.
I went the route of a new PTFE pressure line as I wasn’t sure about the shape of the hard line where it went through the frame at the back wheel. It was probably fine but given the higher pressures and such it was less of a headache and potential fuel problems to run a new line. PTFE hose will also outlive hard line and the car so it’s a nice upgrade for the cost. It also allows easier modification and connections to aftermarket parts.
On my 82 I put the filter/regulator at the passenger firewall so both lines run the length of the car. I cut the existing hard lines and used a compression fitting on the hard line to transition to nylon lines going to the filter/regulator. 3 years so far without any issues. They make similar ones for AN flared fittings too.
I have a post asking the same question also. https://www.corvetteforum.com/forums...-location.html
I mounted the regulator on the passenger rear frame aft of the body mount. I added the clamp to make sure there are two points to secure it.
On my LS swaps I've used the C5 FPR with great success. Always mount them near the tank. Instead of the clamp as shown above I just add an extra self tapping screw to the FPR mounting tab.
On my latest LS swaps I've used Tanks Inc tanks and 255 Walbro internal fuel pumps. On other swaps I've used stock non-baffled tanks and Bosch 044 external pumps. Never had a failure with either.
In the pic above it shows the input and return of the FPR. When you buy the -6 adapters get the ones with the retaining nuts that ensure the fittings can't pop off the filter.
What did you do at the tank? I have run AN6 hoses and fitting at the engine compartment to the regulator and then to the engine, but since I am putting a new tank in ( my bladder cracked ) I think the way to go is compression fittings at the sender and fuel lines at the chassis and then use braided fuel lines and AN 6 fittings between for ease of installing / removing tank if needed.
My C3 was a 71. No bladder in the 71 tank. So I used the stock 71 tank and the Bosch 044 external pump. Along with the C5 FFR. -6 AN hose from the bottom of the tank to the FFR. -6 from the C5 FFR to the fuel rail. The -6 line fit over the 71 gas tank bunge. I used EFI clamps on the -6 at the tank. -6 fittings every where else. Neve had had leak.
My C3 was a 71. No bladder in the 71 tank. So I used the stock 71 tank and the Bosch 044 external pump. Along with the C5 FFR. -6 AN hose from the bottom of the tank to the FFR. -6 from the C5 FFR to the fuel rail. The -6 line fit over the 71 gas tank bunge. I used EFI clamps on the -6 at the tank. -6 fittings every where else. Neve had had leak.
if it’s EFi 3/8 rubber or braided line with EFi clamps then it prob wouldn’t leak before(between tank and pump)the line between the tank and the pump is only at a light suction only and no pressure. Anything after the pump needs to be 100% AN or barbed with proper clamps and hose.
What did you do at the tank? I have run AN6 hoses and fitting at the engine compartment to the regulator and then to the engine, but since I am putting a new tank in ( my bladder cracked ) I think the way to go is compression fittings at the sender and fuel lines at the chassis and then use braided fuel lines and AN 6 fittings between for ease of installing / removing tank if needed.
I don’t like compression fittings and technically I don’t think they are rated for EFI pressures. I know the popular compression AN fitting adapters are used a lot but they say not rated for fuel pressure. I did it and it worked but I was not aware of this small clause.
if you want to do it right with a hard line and AN line. U gotta cut the hard line barb off and put on an AN nut and tube sleeve. Then flare the end to 37* I think which is AN flare size (verify that) then it screws and locks onto a standard AN male fitting. Then it’s easy to remove, can withstand lots of pressure and clean. Hard part is the flare and on the 82 sender there is no room and not enough line to do it correctly.
if you get an aftermarket EFI tank then you will have NPT or AN fittings in the hat and all this will be pointless. Plus you get an internal baffle which a stock tank does not and a working fuel sender that slows the full range of fuel in the tank. The 82 sender doesn’t have the right geometry and really only shows 60–70% of the tanks capacity.
At the tank I used regular fuel injection hoses and clamps to connect to the chassis hard lines. Boring, but effective since these are rated to 100 psi operating pressure/900 psi burst. These had to be upgraded from the factory ones because the new pump runs at higher pressure. All of the tubing ends were beaded from the factory.
This is all with a Walbro 255 in tank pump and the regulator further toward the engine.
And yes, AN is 37 degree flare (same as JIC). This is different than the 45 degree SAE flare on brake lines, just FYI.
I am STILL installing a 2017 LT1 6.2 into my 1978 . I cut the fuel lines up front and modified the lines for AN6 and AN4 fittings which I ran up to the fuel regulator on the firewall. I am installing a new tank and fuel sender. I am wondering how others did the fuel lines at the tank.
Did they modify the lines to match AN fittings, or just clamped fuel hose to the original lines- possibly flare the ends and double clamp ? I am planning on just clamping the return line because there won't be any pressure build up .
Any ideas would be helpful.
Ed
I ran complete new hardlines from tank to engine bay. (Drivers side) proper for LS3 fuel rails. Mounted C5 regulator on drivers side next to gas tank. Hardline up & over gas tank to 82 sending unit. All fuel lines used compression fittings (an ends to interconnect).
Added fuel pressure guage at fuel rail.
Hardline routing along driver side frame rail. (same as factory on passenger side) used same mounting points already on the frame.(vapor lines mounting points)
Since its impossible to run a complete hardline front to backup. I did this in 2 pieces. Here is the join point at the transmission mount.
I received my fittings to run fuel lines from the tank to the lines. I am waiting for new lines to arrive, hopefully in the next week .
I'll take more photos as it goes in.
I don’t like compression fittings and technically I don’t think they are rated for EFI pressures. I know the popular compression AN fitting adapters are used a lot but they say not rated for fuel pressure. I did it and it worked but I was not aware of this small clause.
LS/LT1 swap fuel lines
