Sending Unit. 5/16” or 3/8”, ‘‘tis the question...”

tcb-1

Well Known Member
Supporting Member 1
Gang,
Getting ready to purchase a sending unit for my ‘61. It has a 283, stock build, with an Edelbrock AVS2 500cfm carb. I know the 5/16” sending unit and fuel line was stock for 235 and 283 engines, but is there any advantage for me to bump up to a 3/8” unit and lines? (I’m also replacing the entire fuel line, stem to stern anyway).
Thanks ;)
 

tcb-1

Well Known Member
Supporting Member 1
The prebent 3/8 line goes under the passenger side a frame to get to the fuel pump.
The 5/16 line runs along the frame by the exhaust manifolds to get to the fuel pump

i used nothing but stainless prebent 3/8 inch lines ( no rust ever)

Paul, I am going to use nicopp 3/8 tubing since I don’t have the body off the frame. Been really happy with the flares I’m getting and how easy it is to finesse into the tighter bends as far as brake lines go. I’m afraid that trying to snake prebent fuel and brake tubing from the through the center of the x frame would be virtually impossible.
 

bobs409

 
Administrator
I guess I'll throw this in... When I put a 454 in my 72 Chevelle, I ran it for a few years with the stock 5/16" line and all was fine. I have upgraded to a 3/8 fuel sender and lines a few years ago and never noticed a difference yet.

Now for a race car, I'm sure that extra fuel flow would be needed but for street cars, it might not really be necessary. Especially for the original poster since he's got a 283. Just my thoughts for what that's worth. :D
 

pvs409

Well Known Member
Supporting Member 11
I added new stainless pre bent 3/8 lines to my 62 Impala Hardtop(327/300 HP car) with the body on the frame -but no motor in the car.
I used the factory routing through the X frame.
There might be room with the motor in the car -the pre bent lines come in 3 pieces as noted above -its possible that I had the motor in the car...
Paul
 

pvs409

Well Known Member
Supporting Member 11
The center prebent line has two bends in front of the X frame and you turn that down toward the ground and slide the
long straight section right through the factory X frame holes.
the front and rear section are easy -except running the front one under the front passenger upper control arm
(the control arm needs to be off or tipped up.)
 

Tooth

Well Known Member
Supporting Member 3
I would check to make sure that the resistance curve on the float for 5/16 and 3/8 are the same. If not your fuel gauge reading will be inaccurate. It’s based on tank volume too. If tank size for the 3/8 and 5/16 are the same probably won’t be an issue. I know sometimes smaller engines have smaller tanks... just a thought.:scratch
 

1964SuperStocker

Well Known Member
Supporting Member 3
Gang,
Getting ready to purchase a sending unit for my ‘61. It has a 283, stock build, with an Edelbrock AVS2 500cfm carb. I know the 5/16” sending unit and fuel line was stock for 235 and 283 engines, but is there any advantage for me to bump up to a 3/8” unit and lines? (I’m also replacing the entire fuel line, stem to stern anyway).
Thanks ;)
Since no one actually answered you. No there is no advantage. The fact that you are considering putting the original 283 stock block in would lead me to say do not go bigger. Remember most of us here are performance minded so we jump to Bigger, Better, Faster... An original stock 283 build doesn't have any reason for a larger line. If you had the original 283 tucked away in a corner gathering dust, like my wagon 283 is, and you were stuffing a 383 small block or switching to a 348-409 performance build then yes the larger fuel line would be a good choice. With that said, anyone willing to keep a 283, do a stock rebuild and not jump to a larger displacement would tell me that the 5/16 will serve you well for years to come.
 
Top