Wilhelm Not 100% sure when AC Cars changed the fuel filler cap from The Monza Cap to the Ceandess Lozenge shaped filler cap with the Key hole shaped release.
Looking through dozens of Ace photographs both current and period it would appear the change occurred in the 2nd quarter of 1955.. (April/May or June). Difficult to home in accurately as period photos are not always clear and current photos could depict the Ace after restoration or having had replacement cap fitted over the past 50 odd years.
Please note I have started a fresh thread reference change of components/ fittings during early production of the Ace .... Hopefully we can eventually home in on a more accurate date on many of these subtle changes...[
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From recent email correspondence I believe you have purchased BEX312, being a 1957 Ace it should have the Ceandess Fuel Filler Cap. Copy recently produced with a few surplus units available via Gerry Hawkridge.
Please note you must ordr unit with the correct screw threaded base and you will need to have a screw threaded adaptor collar with extention tube made in order to secure unit to rear wing and locate rubber hose to fuel tank.
I will e-mail you drawing confirming accurate dimensions, later today.
In the meantime enjoy the Ace as it is and replace the fuel filler at a convenient later date.
Keith..[
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