Beginning in 1963 Chrysler mounted fuel filters so the outlet would let the vapor out, minimizing vapor lock.
Carburetion and Performance Diagnosis (Session 188) from the Master Technician's Service Conference
1970 basically same position shown in the Dodge Service Manual
View attachment 1716231336
Then to address restart problems with newer fuels and hotter engine bays the fuel pump was made with an internal bypass. A kit could be added if the fuel pump didn't have this bypass. As explained in the 1972 bulletin, its a tradeoff ( and in my opinion not as good as the return to tank used later). Shown here.
[URL]https://www.web.imperialclub.info/Repair/Lit/Master/291/page06.htm[/URL]
and here
[URL]https://www.tapatalk.com/group...er-fuel-in-hot-temperatures-t1459.html#p13914[/URL]
PS. That braided line is not a great insulator. Get some stainless in there and cover as much as possible with aluminized fibreglass or insulating firesleeve.
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I don't know why a 408 should run hotter than any other engine. Its doing the same work with a different stroke.
Take a look at the factory thermostats, and also the information about gages. We've
had these discussion before.