You can purchase restricted fittings of a size that would be useful for a bypass filter.
Try Weatheread part numbers 431x4 and 1512 on pages 39 and 105
Eaton Weatheread Brass catalog PDF

McMaster has lots more choices; search for "orfice" if this link is not fruitful.
http://www.mcmaster.com/#orifices/=12v4zyq

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-