1987 efi fuel tank in 1973 k10 question

[Mike_The_Grad]

Hey everyone, I'm doing an LS swap for a buddy of mine and decided to go with the 87 efi tank with sending unit and walbro 255 pump. My question is what do I do about the fuel tank filler neck hose size compared to the fuel tank filler connectio of the 87 efi tank? From what I read they're different sizes and after bugging my friend Google for the last hour still not any closer to a solution. Any info? Thanks.

[KQQL IT]

1.75 I believe

[Mike_The_Grad]

1.75 is the size of the efi tank port. And the fuel filler neck from the 73 k10 is a lot smaller than that. I think 1-1/4 or 1-3/8. Does someone make a conversion filler neck hose?

[Dead Parrot]

A quick measure on my 75 C10 shows 1.5" for the filler pipe. Mine is the non-door filler for leaded gas.

It looks tight but maybe an exhaust pipe size converter might work. Or see if you can talk an exhaust shop into making a bend/size converter in the same pipe. Then all you would need are two short pieces of straight hose.

[Mike_The_Grad]

Yeah they didn't change the filler neck hose size too much until the later TBI years starting in 87 I think. It's just strange that for all of the information out there on LS swaps and all of these squarebody trucks that are using a 87 tbi tank for their ls swaps not a single bit of information has been posted adressing the filler neck hose size differences solution. Other than exhaust pipe with a flared end. The 73 k10 I'm working on is also a non door filler neck with the gas cap outside of the rear quarter. It's a dual tank truck. But we are only going to run one tank for now on the drivers side to streamline the process and simplify the fuels system. Originally he wanted both tanks and e85 compatible. But that's a different job for a different day.