I am looking for a replacement for the 5/16 (I think) line that runs from the outlet of the fuel pump, filter and to the distribution block of a Hemi fuel line. I would like to replace it with a 3/8 line. That would also require a 3/8 inlet/outlet filter with the return line and a diffrent distribution block where the lines split off to the dual carbs. Does someone make a kit??

I think Fine Lines makes them.Depends on the car.There is another company that makes lines also but I cant remember the name.You could just get some bulk tuming and make them.Unless its a 100 point resto thats the cheapest route.Rocky

IMO it's not worth it, I'd stay with stock line sizes because getting all the right size fittings is gonna be tough. What matters is before the pump on the suction side, not the discharge size.

It is all 3/8 from the tank to the pump. It sure seems like a potential bottle neck from the pump to the distribution block to have 5/16. From the distribution block to the carbs the 5/16 is ok. I would bend my own lines but still need to find the right filter. The motor is a 528" Hemi with 494 RWHP, I figured this would be something someone else already figured out.

I hear you and I'm sure someone has, somewhere. The suction should always be bigger than the discharge, on any pump system of almost any kind. You ready to go bigger on the suction side?

I'd it drive first and see and I bet it won't slow you down at all.

Why is it that the discharge side needs to be smaller than the low pressure suction side??

Thanks Challenger. I was figuring any restriction reduction on the delevery side would help.
So, on a Mopar fuel pump the outlet side, when you remove the barb and look into the port, is a pretty small diameter. By drilling it out to enlarge it would not result in better fuel flow? (I do realise that there is probably alot of engineering there).

Cool,
Like I said, I'd run it and find out.
And NO I wouldn't run modified fittings.
I know it cost money to buy the fittings and hopefully only do it once.
I'm just telling you what I learned by actually racing and burning fuel. Lot's of racing fuel.

I've also driven my street cars hard off rd and know what it takes.
Moving gasoline is the same no matter what.

540HP Street Hemi here, the stock line from mech pump to T to carbs has not been a problem to 7500RPM.
That said, the car runs 1/2" from tank/filter/elect.pump to the mech pump.
I prefer to filter the fuel before the pump(s).