Thread: Truck trivia
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Old 10-24-2019, 11:38 AM   #14
71CHEVYSHORTBED402
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Re: Truck trivia

Quote:
Originally Posted by special-K View Post
I believe all '68-'72 frames are made the same, to accept any engine offered in that year.

I think the '72 BBC fuel return line only with A/C is related to the A/C to try to cool fuel since A/C tends to bring the temperature up. And the pump to carb fuel line for A/C-only is A/C related because w/AC requires a different pump.
This is out of the part's book. Going by the part numbers, a 1971 402 takes a 6470424 fuel pump only. That pump doesn't have a return line. Consistent with that the 71 takes a single line fuel sender, per the part's book. It's how I found my 71 as well.

Per the book the change occurred in 1972. Couldn't tell you why, but according to the book a 1972 402 with 400 transmission had a return line. I'd only be speculating why the change.
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71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025
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