Fuel sending unit size?

[Bearcuda]

Hey, I think I need a new fuel sending unit, but when I look it up on classic industries it asks if I have 5/16 or 3/8. I don't know because I haven't dropped the tank and I don't want to until I know what size I need. It's a 71 cuda 340 car. Was the smaller size standard on small blocks?

[JS29]

5/16, 3/8 is for 440 and probably HEMI.   

[anlauto]

From the factory your 1971 340 Cuda would have two full length 5/16 lines running from front to back. One is a vent line, the other hooks the fuel pump to the sending unit. Each part requires a 5/16 outlet.

[pschlosser]

The parts book concurs only the 440 and 426 came with the 3/8 pickup.  All others had 5/16.

The sending unit it somewhat exposed on the right side of the fuel tank.  Grab a caliper and measure the tubes coming out of the sending unit, if you want to confirm.  That said, if I need to replace one, I might be tempted to put the 3/8 pickup in just for the sake of performance.

[Bearcuda]

Thanks, 5/16 is what I was thinking since it's a small block. Appreciate the responses

[7212Mopar]

After you install the new sending unit, you might post and asking about the fuel level not reading correct. So do a search and there will be a lot of answers on this forum. Also keep the sender OE locking ring for reuse if in decent condition. If the OE sender works and in condition to be refreshed and reused. At the very least keep it so that you can use it for reference to calibrate the new.