The service manual shows some type of restrictor in the larger of the two vent hoses, see pic. Sure enough that part is not longer in place on my car ('70 GS 455). Does anybody know how this restrictor looks like or what the remaining effective cross-section/diameter is with this thing installed? I think about fabbing something with similar functionality, as I do not want to take the risk and have fuel sloshing out at hard cornering or acc-/decelaration... Thanks a lot!
I believe all that is, is a piece of mesh like filter element similar to the material in the air cleaner crank case filter. You could probably just cut a piece of that filter and stuff it into the hose. https://www.rockauto.com/en/moreinfo.php?pk=5612877&cc=1379763&jsn=414 Or you could also use this, http://www.fusickautomotiveproducts.com/prodinfo.asp?number=TT969
The parts place would be cheaper for the surge tube protectors due the a savings in shipping charges. The one shown by Fusick is correct for the housing without the filter element.