87Formula4bbl

When it comes to fuel lines and connections, I really have no idea so I need some advice. Since I've swapped over to fuel injection, I'd like to upgrade my lines. Car was originally an LG4 so it has some dinky lines (I think too small for the 350, what do you think?). Even so, if the supply line is big enough, I think that the return line is too small for the pump I have (rated at 65gph, 95-100psi I think). And from what I've read it is 5/16", which is an 'odd' size, can't find any AN to hard line adapters for that size else I would just try and use that (need to go from fuel rails to the hard line).

Now if I wanted to upgrade both supply and return lines to 3/8", what would be the best way to go about doing this? The hard lines going into the tank are stock size, what should I do about those? I just dont' see how people upgrade their fuel lines to larger sizes without cutting out the stock lines that go through the 'cap' in the tank at the top and drill them out and reweld the bigger lines in to seal it up.

Any advise is appreciated!

Thank you,
Ben

five7kid

iTrader: (14)

The lines are large enough. They're the same size used on TPI cars.

87Formula4bbl

Thanks five7. I just didn't know how well they will flow (how much power they will support). Do you know if the TBI cars used the same lines as the TPI cars (and V6 cars for that matter also)?

ME Leigh

The fuel lines will support more HP then the TPI intake. More than 350hp. I bet a lot of people on here make way more then that with the stock lines.

five7kid

iTrader: (14)

I'm using the V6 lines in my setup - 3/8 & 5/16.

I don't know about all of the possibilities, but from what I've gathered around here, the "typical" 3rd gen lines are all 3/8 & 5/16. A couple of people have said something about the mid-80's V6's having smaller lines, but I'm not sure I'd take that to the bank. The 4 cyl may also have been different.

ME Leigh

So your saying that stock they should be 3/8 and 5/16 return. I'm impressed if thats what they are. I know i have 5/16 coming off my FP, i don't know if is stock though. It was 5/16 going to my Q-jet, so... I guess i will go measure tomorrow, because i'm curious, i just assumed they were 5/16.

87Formula4bbl

Ok, great. That will save me a lot of time and money by not 'upgrading' them to larger diameter tubing. Now I just have to find a way to connect them to the 3/8" NPT fuel rail inlet and -6AN regulator output (to 3/8" and 5/16", respectfully).

Another question, do you think it is ok to use high pressure rubber hose in the rear to connect the return lines from the tank to chassis lines and the same for the supply, only with a filter between, clamped tight? The filter will have barbed hose adapters, the hard lines will just be slid over and clamped. The question is, will I have problems with that high of a pressure with clamped lines? I don't see why I would since the pump to hard line uses rubber hose and two clamps.

five7kid

iTrader: (14)

Barbed/clamped hoses should be limited to the lower pressures, no more than 10 psi. Use swaged lines for higher pressures.

You might try a search on the TPI forum for the adapter info.

Zepher

iTrader: (1)

Earls and Russel make Hardline to AN compression fittings in 3/8 and 5/16. that is what I am using on my LT1 setup (car was an LG4). We used the same setup on my friends LT1 setup (his too was an LG4 car)

On his car, we put those fittings on the lines on the gas tank and on the lines at the fuel rail with 6an braided hose front to back with the feed having 2 lines, one from the tank to the flter and from the filter to the fuel rail.

On my car, I am going to run the adaptors on my tank, on the 2 sections of stock hardlines on the body, and on the fuel rail.

I've heard people say these adaptors aren't that good, but we haven't had any problems with them.

87Formula4bbl

Wow, thanks Zepher. I knew they made the 3/8 adapter, but I couldn't find the 5/16 one. I even called up Summit and he said they didn't make one. Do you happen to have the p/n for the 5/16 by any chance?

Oh, as for the lines back at the tank, I decided I'll just flare them and patch them with some hard line I got from Autozone. I don't know much about flares, so hopefully I can make the right flare for the fittings (think they said they were double inverted flare). I will patch in a stock TPI fuel filter while I'm at it.

I guess a lot of people are running with the stock 5/16" return line, so hopefully that will be sufficient. I just didn't want excessive pressure building up at the rails from lack of flow in the return line caused by that pump I will be running.

87Formula4bbl

Whoa, nevermind! I guess I didn't look at the picture too closely