Ive been doing some light service on the Ellena car and discovered my Rad cap was not sealing well enough. Seems upon investigation, the cap - from the rubber seal to the stainless ring inside the cap was not long enough to provide a good seal to build any pressure, or hold pressure. Further investigation on various caps of that period (late 50's) it seems there are various lengths due to the radiator cap mounting housing on the radiator. SO, couple of questions to the inside plug 250 experts - What is the correct pressure rating that would be used for this engine and what cap is appropriate for this application, keeping in mind the length needed to properly seal. Appreciate the thoughts and advise on this .