Had a problem with a leaking master cylinder. My car 1966 has non power front disc rear drums. The cylinder I ordered was a Delco 18m1878. The problem that I am having is that the old cylinders valve my plunger would fit at least 2inches inside while the new cylinders valve is right on the edge. Also it was hard while trying to bench bleeding the new cylinder. Both look like they have the same size valve. My question is do you think the only thing to do is to get a shorter plunger because the one I have will not fit on the top hole of the brake peddle and barely fit on the bottom hole. Thanks for any help.