Fuel Pump Line Adapter?

[TravisB]

Hey guys, I thought the fuel pumps were all the same on the small blocks. I needed to change the one on my 69 GMC so I grabbed one off the shelf that I had for my 78 and bolted it on. Then crawled under to put the line to the carb on and find that the line is way smaller than the hole it screws into on the pump. Both trucks have a 350 but I am guessing maybe the 4 barrel carbs got a larger line from pump to carb or something. My 69 has a 2 barrel.

So, to prevent having to change this thing again with a different pump is there an adapter out there to go from the bigger line to the smaller line? Is that a bad idea?

RockAuto cheap pump for 5.7 shows a 5/8" thread outlet https://www.rockauto.com/en/moreinfo.php?pk=3956490&cc=1142389&jsn=404

RockAuto cheap pump for 5.0 shows a 1/2" thread outlet https://www.rockauto.com/en/moreinfo.php?pk=3957009&cc=1142378&jsn=749&jsn=749

 

[TravisB]

Realizing now that this may have been a bad place to post this since the 69 isn't really a square. I don't want to cause confusion so this can be moved if needed. The 5.0 in 78 may have taken the same larger line as the 5.7.

I have found a couple adapters for those sizes but they are all for brake lines. Is the flare the same between brake lines and the fuel lines?

 

[bucket]

Have pictures? Are both lines the flare nut style?

 

[TravisB]

I figured it out and found an adapter.

This was my fault. The 69 has a 307 instead of a 350 which had a smaller line. This can probably be deleted since it wasn't for a square at all but not all small block pumps are the same is the only lesson here. Haha

 

[bucket]

So the stock pump had a 5/16 line and the new pump used a 3/8 line? And you got a reducer fitting to screw the 5/16 line into the newer pump?

Did I guess right? And if so, what do I win?
Lol

 

[TravisB]

Yes, you win. The prize will just have to be the satisfaction of winning for now. If you are through Ky sometime let me know and I will let you have a beer and look at the adapter though.

 

[DoubleDingo]

As @bucket stated, 5/16 on the '69. I forget what I typed in as a search in google, but I got an adapter for Crusty Biscuit that is 3/8 on one side and 5/16 on the other. Someone swapped in a '72 L48 in the truck, but called it a 283 when I bought it. I didn't say anything but I knew the valve covers weren't for a '65 283. They had a 283 fuel pump on it and it was gutless. It was fuel, and also ported vacuum related. I got a 2 port 350 fuel pump, and that adapter, ran a short piece of 3/8 from inlet port to the 5/16 line from the tank. Then 3/8 to the carb. It was a couple years ago, but I will try to remember what I searched for. It is a clean adapter, only about an inch in length and unless you look for it, you won't know it's got an adapter on it. I wish it had 3/8 to the tank, but I don't know if a '69 sending unit with a 3/8 line would fit a '65 tank. You have the option to get a 3/8 sending unit and running 3/8 line to the pump, which may be better unless you are happy with the adapter being there.

 

[TravisB]

If it doesn't start leaking, I am leaving it alone. haha

 

[DoubleDingo]

I don't blame you. Mine runs fine with it like that. But I think it could gain a few ponies if it had 3/8 all the way. I'm not complaining, it gets 12-14 mpg's and cruises right along with the newer cars on the highway.

 

[MikeB]

Funny, but even square bodies with a 250 six used 3/8" line. At least that's true for my 82 C10. Also, an 82 305 and 350 had a return line, which requires a pump with 3 ports. That extra hard line back to the tank is a very nice feature for an EFI conversion.

FYI, I think the adapter is called a "bushing" in plumbing terminology.