Radiator caps.

Has anybody got a surplus radiator cap please? Our project came without one. I'd be very grateful if some one has a spare, even if it is old and cruddy! David Barker Posted by Delagiste 06/04/2018 10:08:34

David - more specifics on year and model.  I cannot help, but perhaps others may. Posted by johnlayzell 08/04/2018 20:51:08

I can't really be certain because our "kit" came with a very nice aluminium radiator which fits inside what I think is a Firefly shell (which we have had to shorten about 2 1/2".)  The cap has to fit on an externally threaded upstand. 2 1/4" diameter and 19 t.p.i. Does that help? Were there many different sizes between Alvii in the '30s? Posted by Delagiste 10/04/2018 13:05:16

The SP25 cap ID is 56 mm (2 7/32”) ID 16 tpi. The OD of 64 mm (2 ½”) is also critical as it has to slide down inside the radiator shell opening.  The 12/50 cap ID is 2&quot; with a very coarse thread, maybe 8 tpi?  You might just have to search on ebay until you find something suitable, like this:  <!-- m --><a class="postlink" href="https://www.ebay.co.uk/itm/Chrome-RADIATOR-CAP-Morris-Flatnose-Cowley-10-12-Austin-Vintage-Car-Mascot-VSCC/392012062192">https://www.ebay.co.uk/itm/Chrome-RADIA ... 2012062192</a><!-- m -->  Good luck! Posted by johnlayzell 10/04/2018 14:42:38

I have just re-checked it and think it's actually 18 t.p.i. not 19, when there's only about four threads to go on it's not easy to be sure. But I reckon it's 18. As to diameter it could be 2 7/32&quot;. Are you sure Sp25 ones are 16 t.p.i John , not 18? It would be logical for the ali rad to have been made to pattern from a Sp 20 maybe.  This is why I asked if anyone had a cruddy one! Posted by Delagiste 11/04/2018 12:39:33

Out tpi gauge looked like 16 , but I wasn't 100% convinced so I asked son Brett to use his 20:20 30 year old eyes to confirm, and he did. Of course, we could both be wrong, but unlikely! Perhaps another SP25 owner can comment? Posted by johnlayzell 11/04/2018 17:39:14

My Speed 25 cap is 16 tpi according to my venerable pitch gauge. So, for that matter is my 12/70 cap which is identical to that on the Sp 25. I also measured that on the 12/60, which is 12 tpi, but threaded externally whilst the later caps have internal threads. The 12/70 cap is part no. N18335 but annoyingly the Sp 25 parts book does not give a part number for the cap. Posted by DeaneHarding 11/04/2018 19:37:44

Thank you gentlemen, it now looks horribly as tho' I need something other than an Alvis one! Looks like making one, bu**er! Posted by Delagiste 12/04/2018 16:13:13

Made one from scratch in the end! Posted by Delagiste 22/04/2019 14:23:42