gas line size

[warren57]

I'm getting ready to run my gas line from the tank forward. The line coming out of the tank is 5/16". The mechanical fuel pump connection is 1/4".
So 1/4" line or 3/8"?? Pump is 80 gph@6-8 psi
Thanks

[NickP]

Requirements are base upon the engine design. If the engine is stock, then why increase the size? A 3/8 line as detailed here is minimized in effectivness by the delivery size (5/16) and the end size (1/4).

[chevynut]

When you say the pump connection is 1/4", is that 1/4" NPT? You should be okay with a 5/16" line if your engine is fairly stock. If you need to replace the line, imo I'd go with a 3/8" line if you plan on higher HP in the future. I had a 390 HP 427 in my '55 and I could run the bowls dry if I really got on it. I don't know if the problem was the pump or the stock fuel line......never had a chance to figure it out since the cops in KCMO (imo) stole the car from me after 3 days there.

[Rick_L]

The ID of a 1/4" pipe fitting is bigger than 1/4". Measure your fittings. Even at that, the pressure drop of one fitting is not nearly as important as 6' or so of undersize tubing.

[warren57]

Sorry for the limited info.
The pump has 1/4" NPT. Engine is a GMP crate 350HO 330 HP, Holley 670 dual feed.