Hey there guys, have a question here as I'm a bit confused. The Buick Grand National sending unit uses a 3/8" fuel feed with a 1/4" return. Now in stock form, this has proved adequate up to a decent amount of hp. However, when doing reading about people swapping V8s into their G Bodies, I keep reading that they need to up the size of the return line. For my car, this is a naturally aspirated 350 Chevy. I would think that if the return line was good enough for a boosted application, that it for sure would be good for naturally aspirated. I don't know how I got that reasoning. But basically, I wanted to know that if I converted to EFI, if that 1/4 return line would be adequate? Thanks in advance!
EFI and using GN/TBI sending unit in Cutlass for naturally aspirated 350 V8, return line too small?
- Thread starter V6UnderPressure
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The factory return line should be fine with a mild 350 if you buy the right fuel pump. If you plan to go use a power adder in the future then buy a higher volume fuel pump and upsize your return line now. High flow + restriction in the return line = big problems. If not, a factory GN pump or equivalent will work fine as designed by GM. You may want to read up on the vent line swap and sending unit mods poeple are doing to provide proper venting. IIRC, there are some good write ups on LS1tech.com
Thanks, we are talking about a 420hp/440tq naturally aspirated 350. This is going to be the deciding factor if I go EFI or not. I want to use the factory lines. If I cannot, I am going to stay carbureted. Now I can avoid all this if I go with an Atomic EFI with the PWM fuel pump which requires no return. However, I prefer an intank setup and do not want to modify the stock lines.
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