EFI fittings for Supply/Return line (under hood) - Which ones?


Aug 7, 2018
Attempting to replace my factory fuel lines from the steel supply/return lines up by the passenger corner to the fuel fitting. From what i read people were recommending the Russell EFI fittings

• 5/16 to 6AN hard tube adapter - 644113
• 1/4 to 6AN hard tube adapter - 641303

But I'm hearing the retainer (part on bottom that threads into fitting) won't go between the two flares on the tube. In fact its the 2nd flare on the steel line that is interfering. Has anyone comes up with a solution for this? I know there is a 5/16 push on fitting (640863) but isn't favored due to the design could possibly pop off. But was that worse than OEM? Also doesn't look like Russell makes a 1/4 one.

I have to imagine there is some solution on the 94/95 cars, just wanting what.
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5 Year Member
Aug 11, 2013
Cleveland OH Area
Hey there friend, I was probably one of the commenters on the thread you found. :) I don't think anything new has hit the market, but I'm also curious if anyone else has found a solution. Personally I think the easiest option is to cut off the 2-part flare and use a compression-to-AN fitting. Something like this: https://www.holley.com/products/plu...rdline/compression_adapters/parts/AT165056ERL

Unfortunately the 640863 was much worse than stock (never heard of a stock one popping off, just the fuel hoses getting brittle over time). Stock used an aligator-clip configuration like the fuel filter which would require a very significant failure before the line could be removed. The 640863 is a weak little clip that is prone to warping and vibration especially near the heat of the exhaust. The 2nd flare may also keep it from engaging completely.